I know this would be a bit counter to the way standard D&D is designed, but I feel like this is a plot hole that would be solved by saying the party members are just incapacitated in some way, not dead, so that it makes sense why they can be revived so easily and why the tadpoles stick around.
Maybe they can introduce a permadeath mode to the game where your party members actually die when they're killed and you see the little tadpole crawling away from the corpse. XD
