Do you want to show all warriors in all buildings, or player has to transfer characters to the guild before they appear in the list? I'm not really sure what is the best way, showing everyone could be very messy, even with filters per building...
Anyway, I believe we need sorting by level and by character name at the teams screen. I don't see the game using buttons-switches so far, when one button can have many icons and/or text depending on the current mode, and clicking on it changes the mode. Such buttons are probably the best bet for filters like name/level.
Also, MC teammates cannot be a part of SE, unless MC is a part of SE too. We probably could set them as his team automatically once you drag MC to a team frame.