I would expect it would have issue with target selection. healing cross team will see a lot of heal onto one char, which might be a bad thing considering the other use of heal is to cleanse debuff.

Granted, some healers don't cleanse debuff on their regular heal, like sakura. Then the problem becomes what if a bunch of them keep going after that one ignited target.... that's going to be wastful... I'd also like to spread that risk.

The ideal implementation of this for me is that a healer will Xteam heal if and only if their own team is all at full hp, so that it is not wasted. Otherwise, I'd rather heals stay in their own team and thus spread the "risk" of wasted effects (either cleanse a clean target or heal a unhealable target)