What happens when a player has X amount of enemies engaged and he reaches 50 threat? Does those enemies go to the staging area or engage the other player automatically?

Thanks,

Javier

They go to the staging area.

The rules, p.22:

Any encounter cards with which that player was engaged are returned to the staging area, retaining any wound tokens that have been placed on them.

I assume they go back to the staging area. That's what we've done in multiplayer when one player is ousted.