there's also HammUEr, which I think carries over more stuff. I wanna say it'll let you place lights, possibly even actors? via Trenchbroom, and have that all just populate correctly on Unreal side.
Results may not be useful, depending on how much you're doing literal graybox VS level design, but— it's really cool!
EDIT: oh right! Also materials and decals.
EDIT2: I think the other cool thing is it keeps your meshes separate, so you don't have to work with one HUGE chunk. Like you can make yourself a bench over in Trenchbroom and place it in the level, pull into Unreal via HammUEr, and then you've got a separate bench mesh too you can instance around as you like.