If you can remove those factors from development, there's plenty ways to subtly buy reliable guide the player using art style, composition, and level design. The trade off is slower play and more attention required, but the narrative of the greatest detective can support that comfortably.

The thing with yellow is its more often than not a speed decision. Either during development we need a quick and reliable solution or there is a fear that the player cannot be allowed to pause and think. Yellow stands out like a sore thumb, it's too reliable for its own good.

I haven't read any of the newer stuff (aside from Praetorian of Dorn) but yeah all the moving pieces was a fascinating read. Knowing the pieces were moving but not always to what end. It's always killed me that you can't really represent that in the tabletop game 😭

Legion gave me my soft spot for the Alpha Legion. It's up there with my favourites in the whole series because it's just so different and intriguing.

The solution here actually seems to have been separating meshes. The scene isn't all one mesh but I'd imported it as a single (combined mesh) import. Breaking it up into a few imports, split by what's touching what, helped a lot.

Same. They definitely have they're own new ways of doing things that I've just not had the time to catch up on. Doesn't help that a lot of tutorial resources feel like the blind leading the blind.

I think so. Or possibly to do with the mesh distance fields. I think they are quite integral to Lumen and having multiple smaller MDFs to measure against is better than a single big one?

I gave it a punt but increased resolution didn't seem to make a noticeable difference. You did put on the right track though!
A larger issue was me being lazy and importing the scene as a single mesh 😅 breaking it up into smaller parts helps a lot to make things less blotchy and more natural.

Some helpful tips in this but ultimately not the solution. Thanks though!
It looks like a larger issue was me being lazy and importing the scene as a single mesh 😅 separating the things on the wall from the wall itself helps a lot to make things less blotchy and more natural.

Possibly, I think it's more likely AO than cast shadows, but I can't find any settings affecting it. I'll take a look at this though.

I'm not convinced it's cast shadows but rather weird AO artifacts. But yeah this is the wireframe.

That would be true in the case of the vent and the box. They're at least touching the wall. Do you know any solutions to it?

Blender is probably the most accessible and easy to learn. We used to use SketchUp way back but I don't know how that is these days.
I was also under the impression Clip Studio had some 3D ref stuff built in? I've never used it though.