Are you keeping the upscale? It would honestly fit better if everything was at 1x. At 1.5x scale, the pixels are kinda getting confused and messed up. So everything isn't as crisp and smooth. The stair's floor and the main floor contrast each other in terms in style where the stairs recede into darkness while the main floor is a lot darker and flatter. The main floor actually looks more slapped on than the stairs because there's no transition between it and the walls. There isn't a lot of coherency to the room as a result.
I personally don't see any greater value in going with a 3/4 view than sideview. It isn't really faux 3D. Sideview honestly has more notion of realism to me, because it obscures the parts that would be affected by perspective. Here there might be a horizon line but there's no point of convergence. Plus with this, there comes a restriction where every floor kinda has a certain "weight" to it because everything is side-on. I think it sacrifices the illusion of depth more than it helps.
Well, if i can Downscale back to 1x instead of 1.25x and Keep Depth, I'll try. Shading can take Care of the Floor, And I'm leaving that part near the stars covered until I can Conjure a transition. but remember that the Angle of view is slightly above eye level, I've attached an image for example
If Done Right Depth Can be achieved in the view, Its just harder. I'm constantly at the drawing board, but its also very fun to do this, i just have to work harder to achieve the Ideal perspective whilst keeping Depth effects. its worth a try, and if it all fails in the end, I still have the normal mapping technique down.
The Idea of the Depth isn't really about a 3d effect, its mostly trying to use techniques not done before in mapping in a castlevania game or not done enough, It more or less giving it an identity.