MCPlayerEvent

The event is not cancelable.

The event does not have a result.

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import at the very top of the file.

import crafttweaker.api.event.entity.player.MCPlayerEvent;

MCPlayerEvent extends MCLivingEvent. That means all methods available in MCLivingEvent are also available in MCPlayerEvent

MCPlayerEvent.getPlayer() as MCPlayerEntity
myMCPlayerEvent.getPlayer();