is there anything that can be done about the imps running into walls? Too many have gotten away because they go where I cannot.

Think you could give imps extra random skills? Like one that spawns a random enemy of the type it had replaced, and one that blows up throwing cluster grenades upon being annihilated, and those that spawn cats... If you can't become the nekomancer, let the imp become the ultimate nekomancer! KELLY CAN'T BLACKLIST THAT WORD HERE!

the Imps keep running into the walls, and i dunno how to stop them

You may be right. I haven't tested this

@muffin do the imps respawn? So far just seeing them on places I go to the first time and wonder if I miss them then they are gone forever

There could be a solution that I'm unaware of. Currently, it has a 25% chance to drop each tier. Apprentice, adept, expert, master tier items.

No idea if it's doable but would it be possible to adapt the Loot from those Imps based on game progression?
If you beat the final bosses for example that they have a higher chance to drop uniques?

One of the most annoying parts about the current progression system is not having the ability to "fool around" with different builds, because uniques are just too limited. (like 8-15 per complete playthrough maybe?)