Ubl vs Ubr : this is an interchange by U/U'. All you need to do is an insert to Ubr position.Makes sense. My preference would be #1. But I am not sure how to do a U-face commutator. I’ve figured out how to D-face exchanges, but sometimes it seems like I just solved 1 piece, rather than the two I had in mind—Obviously, I’m making a mistake with the interchange or the insertion.
For example, your Rfd is the target and you want to shoot to Ubr, then, r d r' will be the insert (Rfd goes to Ubr), U will be the interchange (Ubl goes to Ubr). So, try [r d r', U] = r d r' U r' d' r U' and see how it goes.