Not really seeing too much looking "wrong" with your map, to be honest.

As with most styles, there will be things that seem to work better than others sometimes, and it's often just a question of knowing what options there are, and what (sometimes quite small) tweaks will help make things look closer to what you were hoping for. Sue already covered your points regarding forests, settlement placement, and terrain fill blending, I think.

For your point 3, symbol scaling, sometimes the "correct" symbol scaling just doesn't look right - or maybe not for all the available symbols - so you simply have to rescale the ones that don't look so good to fit more with how you envisaged them looking at the scale of the whole map (not zoomed-in though!).

Point 5, unknown areas. You could add areas of a standard terrain fill with no symbols or other features, and maybe add a new Sheet with a pale single-colour polygon - like a grey or white - drawn over the unknown region, and add a Transparency Effect to that, perhaps with an Edge Fade as well. Or you could try a Blur Effect on the terrain fill itself - again set it on its own Sheet so it's not ALL the terrain that does this! Blur can make the file uncomfortably large if used too frequently, however. Just trying things out with the Sheet Effects is always worth doing, so you get a better feeling for what they can do. If there are terrain features that must be in the region too, you can also partly hide them this way. It really depends what you want the area to have the players might know about in advance.

Try copying the text onto a new Sheet with no Effects on it in exactly the same place as it is now (so the two texts overlie one another). It may work better with the new text Sheet below the original (but still above the floor) or above the original text Sheet.

Alternatively, you might try changing all the text's colour to something slightly different to what it is currently (because the "acne" effect seems to happen when there's something of an identical - or nearly identical - colouring on two overlying Sheets which have certain kinds of Effect in operation). In this case, it may be simply the text Sheet's Effect interfering with the specific colour and shape of the floor fill's patterning.

Go to CC3+, find the drop-down menu "Tools" in the bar along the top of the window, and then go to the "Add Ons" label in that drop-down. That will show you everything you have currently installed, and you can click on any one of those names to access each individual item's description in an HTML file.

However, the sixth built Place is one more suited to indoor musical performances without such adaptations, Spring Festival Hall:

The bright green roof tiles are all made in the shapes of unfurling, fresh, spring leaves, to contrast with the walls and ceilings of the Hall, that bear relief-carved autumnal foliage instead (Embra; what else would one expect by this stage?).

Inside, only the layout plan for the surface-level is provided. Most of the towers have higher, and lower, floors too, which are not illustrated, and which also like to change at times, as the accompanying written notes indicate:

Folding doors allow performances to be enjoyed outdoors on The Plaza or in The Garden, while the Mobile Stage can be raised or lowered to allow more seating in the Grand Auditorium. Despite its odd shape, the internal acoustics are excellent. If you want to perform here - and have the skill to do so - it might help to have befriended some of the musicians from Glass Harmonica Way first (see the Watery Places Streets map). Plus of course, any excuse to use some more of Sue's wonderful red sandstone cliffs!

Constructed Places map 1 is that for the ruler's Crepuscular Palace at Embra. Well, I say "ruler", but she's actually more the physical embodiment of Embra made magically real and living, The Verdant Sorceress, who flies on wings made of summer flowers. Something like the Archfey of D&D, though really more like the deity of/being who is Embra in power and abilities here. The name and flower-wings came from random rolls using tables in A Wanderer's Guide to the Feywild, by Heavenly Spoon, available on the DM's Guild download site (Pay-What-You-Want). The rest is more "me", however. I'd added some details to the PDF and text files for the Crepuscular Palace map before I realised it would be feasible to provide a CA3 drawing of the Sorceress for the Atlas as well, something that needed quite a bit of late revision of both texts and the Palace map. Although there wasn't space to add the full CA3 drawing to the Palace one, I did want to add a suitable link-spot by it. So this is the final Palace map:

And this is the lady herself:

Of course, this is only how she appears in her Elf-like humanoid form, when out and about meeting people, and not trying to terrify visitors unnecessarily. She could seem equally to be anyone else in Embra, or anything at the city - such as a flower, a shrub, a tree, a building, a pond, a floral meadow, a path, a hill, a forest, a cloud, a rainbow, colours in a cloud, the River Clack, or a blade of grass. In a real sense, she IS Embra, in all its aspects, positive and negative. (Oh, and this means the final tally of Embra drawings for the Atlas is now 58, not 57...)

Those who've been following this lengthy series of posts regarding my Embra mapping closely may recall the Palace Heights map among the Hilly Places, and spot the resemblance to this Crepuscular Palace one. That would be scarcely surprising, as they're the same place, here with the Palace a living, still fully extant, building, rather than grassed-over ruins. With an interior:

However, the interior is shown only for the ground level. The upper storeys - which all the towers, walls and great central dome have - are left for GMs to determine, if required, as the elements in it change from time to time.

This is a pretty complex set of tasks you're hoping to accomplish here, but as long as you're happy to put in the work yourself, it should be perfectly possible. That may depend on how comfortable you are working with the mathematics of orbital mechanics, however, and exactly what degree of precision you're hoping to achieve.

I'm not aware of any tools that will allow you to do all of this in one, but you may find some of the tools linked from the Worldbuilding Links and Software page of the Orion's Arm Universe Project website helpful. Note that some of these are only available via the Wayback Machine archival website now, and may use older software types to function. I've not really done much with this in a long time, so can only hope some of it may assist!

Unfortunately, the few folks I know, or knew, who did this kind of thing tended to write their own programs to do it, and while that may be an option for you too, that's not something I've had any experience with, sadly.

Good luck anyway!

Next is the Keyneck Museum, full of wondrous artefacts gathered from across Nibirum and beyond, with displays that change from one visit to the next, although there seems nowhere here to store whatever isn't currently on show. Key Beck might intrigue visitors as well. The water flows in along the west side of the channel from the southwest, round the circuit of the Museum, and then out again down the east side of the channel. Narrow, isn't it? And maybe the name relates to the layout of the Museum buildings in relation to that channel. Possibly.

Place 2 is the Willow Observatory, inspired loosely by the real-world astronomical observatories at Edinburgh, Royal Observatory Edinburgh (which is some distance from the city itself) and Calton Hill Observatory, which is right in the city centre, and the consequent long tradition of watching the night sky from there. While some of that tradition was used to inspire what happens at Willow Observatory (including the annual summer activity of looking-out for dragon ghosts in the all-night-twilit northern sky; you'll have more luck trying a search for "noctilucent clouds", should you wish to learn more before the PDF and text files are available), the setting is purely Embra, as the misty marshes and woods nearby would scarcely seem conducive to dedicated sky-watching if anywhere else. And who knows what you might see on the planets of the Nibirum Solar System using one or other of the great magical telescopes here:

Building interiors:

And the upper interior floor for the Gatehouse:

Plus there are oddities nearby, all of which receive at least some discussion in the accompanying notes.

Overland, Cities and Dungeons are the three key planks for CC3+ mapping though, and it has been mentioned here now, so... 😎

The third Constructed Place is the Abershell Camera Obscura, set in an apparently unlikely open zone, more suited to an observatory, one might think:

As ever, despite the random selection of base-maps for this series of drawings, the choice of what went where was solely my own, all of which decisions were made with the aim of providing additional puzzles for anyone trying to explore the city, when working to ordinary (i.e. non-Faerie) norms.

There are just two actual buildings here; the rest are open domes over the paths. Oh, and for those who might be interested, the Shelly Tearooms are famous for their exquisite range of ice-creams:

While the Camera shows views of the surrounding scene from its darkened inner chamber, as might be expected, under the care of the featured text's magically-skilled Water Faerie operator, it can show many other things and places too. And when you step out the door, that might be where you'll be. Only if the scene changes, the Camera building won't be there to take you back...