Well, Steven and Steel sort of match...
Lorelei was a maiden (see: siren) who lured seafarers to their deaths...
Falkner's English name apparently means "one who trains falcons."
Jasmine sounds like a mix of "jazz" (either a type of music or a ringing jangle of metal) and "mine," like an ore or gem mine.
Clair could be related to "air," which many dragons use. By flying.
Tate's name could come from Meditate... not sure about Liza. Maybe from "lie"... and, um... er... "zuh"?
Juan (Sootopolis Gym Leader in Emerald and a bit player in R/S) is similar to "one," like "number one" or a reference to him being a solo performer.
...By the way, don't forget Janine, Fuschia City Gym Leader in GSC.