We finally got the OK to make these changes, so they will be going live in 1.19. Thanks for the posts everyone, and I hope you all find the new class abbreviations easier to understand.

Gladiator = GLA (no change)
Goldsmith = GSM (changed from GLD, because of similarity to Gladiator)
Leatherworker = LTW (changed from TAN, thanks Enyyx!)
Conjurer = CNJ (changed from CON, just because)

(braces self for further outcries...)