Your game is FANTASTIC!
Unfortunately I think what you're trying to do with non-square collision boxes is not what 'bump' is intended for - from github:
Lua collision-detection library for axis-aligned rectangles. Its main features are:
bump.lua only does axis-aligned bounding-box (AABB) collisions. If you need anything more complicated than that (circles, polygons, etc.) give HardonCollider a look.
When you call world = bump.newWorld(32), you've set the cell size to 32 x 32 and that's how bump works.
Still, there's the physics library - that has much more sophisticated collision detection but it's a lot harder to use.
https://love2d.org/wiki/Tutorial:Physic ... nCallbacks
What shapes in your level were you trying to do non-square collision with? Maybe you should attach your tmx file? Your game seems to be working great just with bump, I'm curious where you're encountering bump's limitations specifically?