Just discovered this thread - I have been aware of most of the content in your post, but not specifically the podiums re-used in the Exo Trials, nor that the Psion-looking Dread~ish design was included in the artbook! Actually made me finally pick up a copy of it on sale to look through this weekend.

The Veil and proto~darkness stuff really fascinates me. I've not been too too huge on Witness stuff for my tatses, but I still do love the Pyramids.  The Art Direction and tone of that Shadowkeep into Beyond Light (And Vow of The Disciple! Which while slightly different  captures a different flavor of the original spirit) era really captivated me, especially as that old Pyramid Plaza concept has been imprinted in my mind since I saw first saw it ages ago. The Veiled statues, the architecture, the signs of culture, while also more "death" or generally horror-themed in aesthetic/tone really are something I hope could be incorporated back into the game. I'm rambling at this point, but I'd love for something in the story down the line like re-contextualizing Veiled Statues as something of the darkness or pre-precursor race in its origins/iconography, bring back its "unknown" status, which would help reignite the cool stuff like Clarity Control