well honestly in cata you only really had
exploration (super easy),
pvp/bgs (grind, I included it in my original suggestion),
certain dungeons and old raids (very few relevant things when most of them were closed or buggy as hell),
there were 0 chances of getting loremaster when only 2-4 zones per continent worked well enough to get the respective achievement,
professions have already been stated "maxed no recipes" so that's the same,
and reputations - if you can't give everyone a "hey you were exalted with this faction before so you will be now too" (sounds like a lot of work, or none at all) then just granting the max achiev someone had on cata regardless of the counter may be possible