'Psychic' being used as a synonym for 'psionic'. For me at least:
While I can see primitive societies conflating the two (much like how Urbolg considers spacefarer technology to be magic), I don't think a society as advanced as the UGC would do the same thing.
- 'Psychic' carries connotations of actual magic, including not only what we see psionics do but also things like predicting the future (non-scientifically, of course), communicating with the dead, etc. that don't belong in TiTS, as well as mysticism and other unfalsifiable, pseudo-scientific (at best) beliefs*.
- 'Psionic', while still being sufficiently not well understood that it is effectively magic, doesn't carry those fantasy-esque connotations (at least, not as much as 'psychic' does) and sounds like something that can, in theory at least, be described rationally and scientifically.
*While it's okay for such beliefs to exist within a purely sci-fi universe, having those beliefs be correct in the same way as they would be in fantasy isn't, as that kind of defeats the purpose of the 'science' part.
Just saying that one term feels more scientific to you isn't really saying why they shouldn't be used as synonyms. Seems like this is more a gripe about your preconceptions than it is about the game itself.