I guess we can all agree that healing a specific target can be difficult if there are many teammates in the line of sight. It’s even worse if one mate is close to dying, you try to heal them but it hits the 100% healthy player instead - and you lose all osmosis stacks.
My suggestion: only consume as much osmosis orbs as much healing was done. Healing 100% healthy player should not make all three orbs go to waste. This will allow Alani re-apply the healing to proper player once she misses and hits healthy target by mistake.