The next, fifth, group of Embra's "Places" is the Hilly Places of Interest, linked from the highlighted "Official Guide" map's inner circle segment:

Quite a packed link-map this time, with six individual mapped places to show, as well as the condensed "Streets", even if just four such routeways had to be set-up on one map this time.

Two neat knotwork designs reworked from the Dover Clip-Art "Celtic Borders on Layout Grids" book provided the focal elements in the map frame design here, once rotated, with a simple linear connecting outline to help highlight them, the curved piece and triangle's slope hinting at upland places at least, although another of the figurative Dover book designs, an eagle, was used on the other "Hilly" maps in this set as a further concession to upstanding terrain.

As far as I can tell from the FCW file, although you have two separate arc lines for the sides of the polygon you're wanting to draw, you have multiple entities for where the straight end pieces should be, so I'm not sure which are the "4" entities you're trying to connect.

The rectangular room that the top of the two arcs are adjacent to consists of three entities, all on the "temple area" Sheet, one on each of the BACKGROUND (FLOOR 1), BACKGROUND (FLOOR 2) and WALLS Layers.

The corridor rectangle at the base of the arcs consists of two entities, again both on the "temple area" Sheet, with one each on the BACKGROUND (FLOOR 1) and BACKGROUND (FLOOR 2) Layers.

Now, as far as I can tell by zooming in, your two arc lines do not connect with ANY of these five entities - or sometimes one end of one arc might, but not the other. So I think the problem may be that you're trying to create a polygon from lines that don't connect with whichever of the entities you want them to at all.

You may find it preferable to create the polygon you need from four simple lines such as you have currently - that is, zero-width black lines - then convert those to a polygon of the appropriate fill. As long as it's on the correct Sheet, it should flow into whichever of the other polygons you need it to.

You may want to rethink how you're drawing the map overall before that, however, as you can only apply Effects to Sheets, NOT Layers, and having all your floor and wall polygons and lines on the same Sheet means they will all look very flat, and hard to tell apart. The three Layers I've mentioned for the entities you have drawn already here would be better as Sheets, with all those Sheets on the "Temple Area" Layer - because the Layers simply act to group all these Sheets together (so you could hide everything on the Temple Area Layer simultaneously, should you choose to, for instance). Just a thought.

Not sure if this will solve your problem, but if not, hopefully someone else will have some more useful suggestions.

Which brings us to the last map in this group, covering the eight "ways":

While the seven streets were constructed randomly from the simple system I'd devised and used previously, the railway needed some further adaptations, reducing the angles turns and junctions could have, and such like. In drawing the final maps, I kept the roads deliberately free from as much obstruction as possible (vegetation and the proximity of the properties along each), since the essence of Travelling Places relates to movement. In the accompanying notes, I've suggested GMs should allow speedier normal movement when using any of these routes, as long as the party sticks to the way itself. And naturally, there are oddities. Such as the large, complex building shapes along Candlemaker Row, where sadly, I fear the giant standing candelabra that light this route at night will be barely visible, and likely unidentifiable, at the Forum's resolution on the above maps. So let's try this view instead:

That weird loop in Stave Lane came from the construction process alone, which was a pleasantly amusing surprise when I plotted-out what the dice had rolled for the first time, especially as it made Stave Lane - a name yielding expectations of being straight and direct - one of the most convoluted of Embra's mapped streets!

Heisenberg Terrace, naturally, isn't always there, while the bazaar in Cat Hall is run by a humanoid feline, Shrew Dinger... Go-By Street is easily missed too, without care (aside from being a test for people's knowledge of fantasy literature; a good spot to place The Genuine Magic Shop, perhaps - despite its different author). The literary origins of Everon Road's name might be an easier test though.

As for Runaway Railway, aside from the real-world city of Edinburgh (very loosely the inspiration for some of Embra's place-names, as well as its actual name) being a major railway centre in Scotland, it also has the surviving remnants of a far earlier horse-drawn passenger rail-line, the "Innocent Railway", so I felt I had to include a railway of some sort in Embra. It's obviously short and simple, though as with everything else in Embra, its size can be as deceptive as GMs require. Rather than get bogged-down in detailing the line's operation, I chose to have the rolling stock run by the magical forces of electrickery (see Wyvern Citadel on this, if necessary). Conveniently, the featured text - and remember, these things were chosen randomly! - involved lightning flashes, which made that decision very easy.

Travelling Place 1 is Toll Cross, which as we see, is an unusually heavily built-up area, surrounded by dense greenery, beyond which is open grassland or moor:

While the base-map was a similarly heavily-urbanised area, the nature of Toll Cross (and indeed even its final name) derived chiefly from the accompanying featured text, and especially that demonic satyr figure. The Impassable Hedges mean anyone wanting to visit the shops or houses here, or even just pass through it directly as a crossroads, is channelled into using one of the four access-routes. Then I adjusted the layout of the buildings slightly in places so those on foot can get to only a fraction of the properties inside unless they pass through the central Boulder Square, where Guess Who waits, like a spider in a web... This view is with the labels turned off to get a better impression of the settlement:

This looks a bit odd (or at least, it's meant to), with some strange rooflines, and what seem to be many towers. An extract from the accompanying text and PDF file may help explain:

Despite the range of building shapes and sizes, they all have just a single accessible storey at ground level inside, as the toggled view to show the building interiors indicates:

This also shows just how much some of the rooflines, and particularly those horn-towers, don't marry-up with the building outlines, yet the buildings, thanks to their lack of internal connections, further help block any attempts to avoid using Boulder Square. And if you try to fly in, it turns out those roofs aren't so immobile as they may appear...

Fourth in the sequence of Embra's "Places" are the Travelling Places of Interest, as usual, accessed from the relevant part of the inner circle on the "Official Guide" map:

This takes us to the link-map, though this time there are just three link-spots on the diagram, two individual locations, and a group of eight "ways", rather than streets, as here, one of the "roads" is actually a railway (which features as the backdrop extract for all eight, primarily because it was a handy size and shape, and in the correct orientation without needing any adjustments):

The map border decoration was kept quite simple, as it seemed best to highlight the "Travelling" concept with something quite clean and direct. I toyed with drawing something quite severe of my own devising for the knotwork, though all that survived of that here was the simple, single line linking the corners (yes, I know, not much to show for it!). The basis for the little knotwork eagle heads - again seeming apt for "Travelling" - came from that famous Dover Clip-Art "Celtic Borders on Layout Grids" book once more, which were handily linked by a single line there too.