Having been a life long Boba Fett fan and owning many, many reference books, replicas, etc... I must be blind because I've never noticed the on-screen T-Visor to be "wonky" on the left side.
After looking at Bobamakers helmet and reading the discussions, you guys are adamant about it, yet looking back at the original white Boba that Ben Burt introduces in the video (and other reference photos) I can't seem to see it.
If it did slip through somewhere, surely that is a mold mistake when it was been made? I would have thought - also with Jango's being perfectly straight - that the designers/makers intent was to have it straight?