Tongues of men and of angels has been explained ad nauseum -
“Tongues of angels” is frequently used as a vehicle to posit ‘angelic speech’. That entire phrase, as well as a few others in that particular part of Paul’s letter, is 100% pure textbook hyperbole no matter how one wishes to slice and dice it. There’s just no getting around that. In all instances of angels speaking, it has always been in a real, rational language. In fact, in traditional Jewish belief, angels can only speak and understand one language; specifically, the sacred/sacerdotal language of Judaism, Hebrew. Paul, being a Jew, would have known this, which lends further support for his intentional use of hyperbole.
1 Cor.14:4 - Yes, because he’s the only one who understands what he’s saying – no one else speaks his language; thus, he’s the only person benefiting. That's not, however, what Paul would like to see happen. Throughout his letter, he calls for clarity and understanding at a public worship such that all may benefit, hence his call for an interpreter.