As much as I adore Tenshi, between her and Yukari, I have to say Yukari makes a lot more sense to return for this game than Tenshi.
That might not be necessarily true ; say Kokoro's profile for example : her ability over emotions supposedly has some kind of relevance in regards to the incident : in other words, stuff that goes around the lines of emotions or the like may prove to be relevant. And who, besides Kokoro, seems to have some ability that is related to that kind of stuff ? Tenshi, with her sword of Hisou which does some rather hard-to-explain things to the spirit and temperament. Depending of how relevant that emotion related thing mentionned in Kokoro's profile turns out to be, Tenshi's ability alone would make her a rather pertinent choice for the game's roster. Like, maybe there'd be some aspects of the incident that would be best explored with Tenshi.
While it is wholly possible for Tenshi to be the Shinmyoumaru for AoCF, in the sense where the part she plays in the story will be purely filler or overall minor in the incident, it is also more than possible for her to play a major role, although there's hardly anything at hand to suggest which direction things could go at this point in time.
Not saying Yukari's choice is inopportune or anything, just that there is a fairly valid reason for Tenshi to be in this game.