Do Special Forces members cross train with other Special Forces MOSs?

Yes that is specifically part of their job and integral to the way the team is designed the way it is. Each team has a junior and a senior B, C, D and E. The junior is learning his craft and the senior is the subject matter expert for their skill and responsible for training the members of their team. Members of the teams are supposed to be cross trained on each other's jobs as well. It creates a redundancy within the skill set. If you are operating in a remote area you can't afford to lose all your commo or medical capabilities just because you lose one guy.

I wouldn't be surprised they train with civil Affairs & psychological operations personnel. We are all on the same team.

Ideally, everybody should know every other team member’s job. That ain’t happening, but you get just enough cross training to fill in in a pinch.