Gnomish Greetings!
I am pretty certain that the game mechanics are treating Tinkering as a regular trade skill and not a racial trade skill and only allowing 1 TS to get above 200. I already have Jewelcraft at 250 and I have done over 100 advanced tinkering recipes and my tinkering skill is not going past 200.
From the Clockwork Tinkerers Union wayback website:
Q: I thought you were only allowed to go over 200 in one trade skill. Can I go over 200 in Tinkering if I already did with Blacksmithing?
A: According to the notes on the fishing skill at castersrealm, only one global trade skill may exceed the 200 skill cap (a.k.a. "Specialize"). Poison making, Alchemy, and Tinkering are exceptions and can indeed go over 200 even if another trade skill already is.
http://web.archive.org/web/200206070...y/ctg/faq.html