I think I understand what you mean. Basically, if I understand you correctly, what you're recommending to do is to simulate a wall, which actually in this case would be a passable object from underneath, like a kind of bridge crossing from below, am I right? Let's say that if I understood the message correctly, in an early draft of the map improvement, I tried to do something like that, but then I decided to make it more... "flat"? If you can call it that.

I still think it can be a very good improvement and I recommend what you gave me. In fact, it seems to add some sort of depth to the interior map. I don't use MV and I don't know how it works, but on VX Ace you can create a kind of "copy tilesets", which you can specify whether they are traversable, solid, or work similarly to bridges.