Thanks for the report! I've never noticed that because I don't use multiplayer myself, and usually scale my character to 70%. In case you're wondering why the display got messed up this way: The mod creates a new surface for every supported character prototype, and puts the preview characters of all players in a row on that surface. The preview characters were spaced 3 tiles apart from each other, which is OK until the scale factor is greater than 300% -- then the previews of the different players start to overlap. I've added a migration script that will destroy all preview surfaces with everything on them. When you continue your game, the preview characters will be recreated 10 tiles apart from each other.
Can you confirm that this works? I hope I didn't introduce any new errors, but one can never know. :-D