Fair enough, I'll do some cross-referencing with the OS data to see if it's indeed the right landscape compared to what I see in-game (ignoring photoreal scenery).
Edit:
Seems I've got it working now, PlacePointsInPolygon was missing a INHERITPARENTATTR at the end and I accidentally renamed the .toc file on the output so it wasn't overwriting the old one I had (figured that out after I literally trimmed the entire area down and wondered why everything was still showing up).
I just need to play with ReplacePolygonByBuildingRectangles now as some of the more complex polygon shapes are displaying in a weird way (and with different roof types unfortunately, but unsure if I can do anything for that).
Edit 2:
I think I'm at a point where complex polygons need to be done manually and the only way to have the same roof/building is to remove all the other ones from the building_textures folder as it seems AFS2 just chooses one at random. I also noticed some rotation issues (houses on a hill), they'd either be floating or be in the ground but I don't think much can be done about that unless I design them manually and place them on the map or so.
Anyhow I'm happy with the result now - Day Screenshot / Night Screenshot. Perhaps the next step is getting the Edinburgh building textures and finally the airport.