The reaction effect is once per turn, once per ability. So as long as the ability is changed or reintroduced, it can activate again that turn. So yes, twice in a row.Comatose certainly does announce itself on arrival, just like Mold Breaker: "Komala is drowsing!"
What about Role Play and Skill Swap? Even if your own ability isn't normally one that uses a visible pop-up, Role Play makes two ability pop-up messages appear: one for the old, and one for the new. Does that mean you get to use your first move here as well, possibly even twice in a row? Then you have Skill Swap making two ability pop-ups for both players.