Why a larger Taranto strike could change Crete

Would two additional Royal Navy carriers make the battle for Crete impossible for Germany?

They could change it substantially, especially if a larger Taranto strike removed the Italian fleet support needed for the amphibious part of the operation.

Two extra British flight decks would not automatically decide the battle for Crete. The German operation became much more dangerous when Italian naval support made an amphibious reinforcement effort possible. A larger Taranto strike that removed the Italian battle fleet would make that commitment far less likely. Additional carrier aircraft would also strengthen the air operation around Crete, so the counterfactual changes both the supporting fleet and the available aviation.