Checking this Annual issue following Julian's query, there are further oddities about it.

Creating a new map file for a test drawing, I found there are no effects on either of the mountains sheets in a new file (the sheets set-up is to have the TERRAIN HILLS one immediately below TERRAIN HILLS 2, and TERRAIN MOUNTAINS below TERRAIN MOUNTAINS 2). When I copy those effects over directly from the Scotland map, and draw using the mountain drawing tool, I get pitting on the TERRAIN MOUNTAINS 2 sheet, just as Julian says. However, if I try drawing a new area on on the TERRAIN MOUNTAINS 2 sheet of the sample Scotland map using the default tool, that ALSO shows pits, unless I keep the area small and simple!

Both the TERRAIN HILLS sheets do come with their Glow effects emplaced in a new file, but there's no pitting with them. I wonder though if that may be because the default hills drawing tool uses only the Solid 10 bitmap fill, rather than anything textured. The default mountain tools both use the Land Brown CA91 fill.

You might also try a search on the Forum here for "Hatch style", as there have been a few folks who've previously created their own, and some of the information brought up that way might be useful.

However, I didn't find any obvious file complexity limitations mentioned, so it might be something less obvious, maybe something as odd as the length or nature of the filename, or some extra "invisible" entities in your drawing. Given the Hatch Styles are all just ordinary, if small, FCW drawings though, I'm unsure what else might be happening in this case.

If I copy the file into the CC3Plus/Hatch Styles folder, I can see the file name. However, when I try to create a new tool with it, the program crashes.

It's possible the file may be too complex to be used as a hatch style, as the ones I've been using recently (from CA20) have all been very basic, just a few simple polygons at most. But I really have no other ideas right now; sorry!

You should be able to create a new drawing tool using your hatch style by taking one of the existing ones that uses a hatch style (for ease), and saving it as "New", using whatever name you prefer.

You'll need to set up the hatch style though NOT in the "Properties" section, but in the "Outline" one, as an "Extra entity", clicking the "Properties" button. Under the "Hatch style" list in the "Custom tool properties" pane this "Properties" button opens, you'll need to scroll through the list to find your hatch style, and then click it. Then OK everything, save the new tool, and test it out.

Hopefully, that'll do it! If not, I'm sure one of our resident experts will leap to your aid - good luck!

These are interesting experiments. It's something I've tinkered with a little before, and it is tricky to get the look right.

There are two further possibilities here, I think. One would be to try just using the Mike Schley clouds, and see how those work out. A possible trick might be to use some inverted dark hills for the underside of the clouds (these might need resizing, and testing out different varicolor options); not sure about this latter. The other would be to add some more clouds elsewhere over the map in the style of those you already have. Their isolated nature right now is drawing too much attention to the contrast with the ground, I suspect. More clouds might help disguise that.

You might also try using the Alyssa Faden clouds (if you have the Annual with them in, at least) as an alternative, as the shadows on those would help with the "multi-layered" cloud concept, and some would work as just darker clouds. They're more similar to the cloud forms you have now than the Mike Schley ones, certainly. The Mike Schley ones do have gaps in them though, which might make them seem more natural over a Mike Schley landscape. Those options are a bit limited though.

In terms of aerial creatures, I've a vague recollection of a winged dragon on a north pointer in one of the mapping styles (which would need work to extract just the dragon, and which in any case I can't now find, so may simply be misremembering...), but if you have Dungeon Designer 3, there's a top-down cockatrice which could just about pass for flying, I think. However, there's a greater range of options in the free Dundjinni symbols - dragons, birds, bats, other flying animals, etc. If you don't have those, you can find the link to them here, though they do need some care to install correctly.

Good luck for further progress!