There are already few UE3 games on Switch and one of them got 60 FPS mod (Bulletstorm).You may need something more than just a mod to run A Hat in Time at 60 fps on Switch, that engine is barely compatible with the system...
It's so strange that they locked it. Then again, it's unstable as fuck on PC so I guess the Switch isn't really better.There are already few UE3 games on Switch and one of them got 60 FPS mod (Bulletstorm).
In case of this game it looks like it needs editing romfs, because game is locked at 32 FPS, so exefs probably is not the one blocking FPS. And UE3 files are kinda messy to edit, because devs like to change many things in UE3.