Has Teachdaire showed up in any of the adventures? He gets a few paragraphs in Vice but I assume that's basically it, except for a few odds-and-ends namedrops in Street Legends and the like?

Not that I know of.

Good old Teachdaire, second most dangerous non dragon/ie npc in Shadowrun. Improved reflexes 3, killing hands, maxed muscle augmentation and toners, titanium bone lacing, and an adrenal pump.

Among other craziness, yeah.