Hey @manavortex,
I'll bet there's not enough demand for that feature for Peter to consider it, but I think it's not a bad idea at all.
Doable.
Doable.
See this thread:
Allow a Macro to Pass Through its Hotkey (Keyboard Shortcut)
Here's the sort of method I would probably employ.
Conditional Execution Based On App-Running v2.00 (ccstone).kmmacros (7.4 KB)
And by preference I would have Keyboard Maestro select the menu item belonging to Cmd-U rather than sending the keystroke.
I would only send the actual keystroke if the Select or Show a Menu Item action didn't work with TotalFinder.
I don't use TotalFinder anymore, so I can't test myself.
-Chris