Actually, Ulthwe would be pretty hard to beat w/tau (and is, at least using my army). The seer council is rock hard, and not that expensive if you use them as anti-char snipers and guiders. All my 45ish guardians have cover saves, always, and a weapons platform. And then my WS can just zip up behind cover, and then unload its nasty payload of banshees on the lines. And my D-cannons take care of those CTM(or, rather, tau jetpack) suits like there aint no tomorrow.
I would just ignore the council, stay out of LoS (of Mindwar), and of SS range. you should be good. I'd worry about the assault troops, more.