As for pulling the name of whoever the character is currently assign to...I have no idea. But, here is what I do know how to do: If the character sheet has a field with the player's name (and its filled in) you can pull that data, but you will need that field's name to do it. Normally, it will be called "player_name" so @{player_name} would work, but there is no guarantee. The character sheet entries are, essentially, overly complicated ways to display the attributes listed on the Attributes & Abilities pane of the character journal. If the character sheet doesn't have a player's name entry, you can put on in the Attributes area. This will have to be done manually for each character. They should be able to go the settings area (in the chat area of the Roll20 interface) and change their display name. As a GM, I delete what's there and leave it blank. The player's may be able to do the same.
