apparently, whenever I go to a multiplayer game right after fighting with Uke (which does not concern the option to join a random server after beating Uke three times), my tori's joints become impossible to control, and when the turn is over, my tori makes a random move- similar to when you cannot control Uke while fighting him.

should be a script error, if I do not know how to fix it I'll help you
Press ESC> Settings> Utilities> Scripts, below you have the script called unloadscripts.lua just double-click it

A faster way to do that is /loadscript then say anything, and it will try to load a new script and fail, but you can also just say to load script unloadscripts.lua.

While this is completely valid, you can even use /ls so that this is even quicker to type.