While you edited the Teebo text, you can correct that he isn't bugged anymore. His stealth works now as intended, just at the time he isn't needed anymore.
To be honest I'm not sure if he still is a farm, Zader solo on auto needs decent speed mods or Jyn or Rex, but it's definitely the path to go for good Rancor scores. Sure you can build a Teebo team for use until level 82 or so but I think it's better to concentrate on gear for Arena (and Zader Rancor team in advance).
Jyn and Rex certainly make the Zader solo a lot easier, but I don't have them yet. So I need to shift speed mods from Arena to Rancor team (TFP and Sid about 220, Vader, QGJ, EP about 180 speed is good for me).
That said, Teebo leader can actually be useful in other places, making him still useful, but he is far behind ships in my farm order (and now I probably would farm Bodhi ahead of him).
