I'd drop Young Legacy down, she has the raw potential, but hasn't honed it yet, as you mention.
Meanwhile Tempest was a diplomat before Voss destroyed his homeworld, so he was a proffessional politician in a race of philosophers. The language barrier probably led to some troubles, but I bet he overcame that quickly enough.
Scholar seems to spend his time mentoring other people, comforting Expat, mentoring Wraith, he even has conversations with alligators, and they don't try and eat him. Also, we see him making a deal with Wager Master, I'd rank him up in tier 1 or just below.
Ignoring team leader tachyon, I don't think Tachyon would make a great talker. In the one comic issue we've seen so far (which is at the start of her career it seems) she is pre-occupied the entire time she is talking to Legacy, she moves too fast to make a full connection with other people and because she is so brilliant she may assume others follow her thinking when she is in reality leaving them in the dust. Also, her rejection of Friction led to that villain being created, she probably comes off as harsh and uptight when it comes to lab work and isn't the best at socializing, so, I'd say average at best.
Sky-scraper is dealing with a language barrier, but she also seems charming and held a high-rank in the rebellion on Dok'Thorath, so I'm not sure I would say socially inept, just dealing with severe limitations.