The other key element is the Color Key effect MUST be at the top of the effects list for that Sheet, or it doesn't work.

Your first comment sounds like the pink shape is being drawn on the wrong sheet. If you're using a drawing tool to create it, that may be set to a different default sheet than the one your Color Key effect is on. If so, it's easily changed by simply carrying out a Change Properties command immediately after finishing drawing the shape - so before it vanishes (you can check to see which sheet it's drawing on while you're drawing it in the information boxes along the top of the CC3+ screen).

I'm guessing that the fractal poly's ending up on the wrong sheet too, as there's no reason it wouldn't work properly just because it's a fractal shape.

Don't forget there's also the standard CC3+ B&W overland style, CC3 Vector BW, and if you have SS1, there's the Fantasy - Monochrome and Handrawn - Hollow (varicolor, so choose a suitable black for the lines) options. It's easy to forget these amongst all the many Annual options, I know!

Some of the varicolor sets can also be changed to actual, or more-or-less, B&W too, with a bit of experimentation.

Plus, depending on what sort of area you're intending, it may be possible to enlarge the symbols to keep them clear enough when resized (although this can lead to pixellation).

Depending on what style you're using, you may also be able to add a Whole Drawing Greyscale effect using the RGB Matrix to shift everything to look black-and-white.

It may help you decide how and what you'll need to draw by finding a real-world 19th century map that you like and think will work for what you're intending (suitable for the size and type of area you want to map, for instance). Then take a look at the thumbnail images for the various Annual issues that Loopysue created elsewhere on the Forum, to see if any of those match closely enough to what you're aiming for. Each thumbnail links to the correct issue on the main ProFantasy website, where there are different examples of the same style in use, which again should help you decide which might be better for what you want.

This is a very impressive and detailed map (speaking as someone who's mapped various parts of these same islands at various scales over many years)!

Appreciate this is for game use rather than historical precision. However, the lines of both the Antonine and Hadrian Walls are a little off their actual ones - Hadrian's Wall follows along not far from the north bank of the Tyne in its later eastern stages, and ends at Wallsend (surprise!) on the north bank more or less opposite Jarrow on the south bank (at this scale), for instance. Not sure how important this may be for your purposes though 😊.

Seeing what else has been labelled, it may be worth thinking of adding some names for the more important old Roman roads, as some at least were still in use by the c.560s CE and later (some major roads still follow their lines today), and a few of the surviving names seem to have their origins in the Old English/Anglo-Saxon language.