I made a small addon for Blender to handle renaming.
UBX is strictly a EDIT: rectangular prism, USP is strictly a sphere, UCP is strictly a capsule. UCX is for convex shapes, which will likely be most of what you’re doing. If the collision shape is non-convex you need to split it into more collisions meshes until it is.
I use Blender tools, but those tools do use the default FBX exporter.