With a properly gemmed and enchanted restodruid, and with double mana-trinkets + spiritflask,
I managed to reproduce endless 30 healer using the bot instead of manual play.
The key to getting the endless stages is to interrupt / crowd control the mobs where possible and needed,
so the CR can't do it on it's own. Just turn tyrael off when you need to cc for a longer period, and remember that the spike damage is at the beginning of a wave.
The most important mobs to interrupt are the AoE ones, primarily the hive singers, but also the fire throwing ones.
You can also stun the big guys before they enrage, resulting in less spike damage at the start.
I'd say that this will always require some manual play as long as no-one makes a specific hardcoded behavior for the whole thing, but once you learn it's not that hard.
I managed to get to wave 57 with oracle in PG-mode, my best is 74 playing manually, so I'd say the cc does a pretty good job considering the complex nature of PG's, and the fact that I switched it off 2-3 times per minute to cc properly.
As for the other modes, I imagine that damage might be easier to script, while tanking will be hard indeed.