Below is what I'm trying to use:
/petattack [@target,harm]
/petautocastoff [group]Growl;[@focus,exists]Growl
/petautocaston [nogroup]Growl;[@focus,noexists]Growl
/petautocastoff [group]Thunderstomp;[@focus,exists]Thunderstomp
/petautocaston [nogroup]Thunderstomp;[@focus,noexists]Thunderstomp

But after seeing the other issue with some modifiers not being recognized, I stripped those out and tested it again with the same results, using these simplified modifications:
/petautocastoff Growl
/petautocastoff Thunderstomp

/petattack, /petautocastoff and /petautocaston both appear as purple text, so I assume it's recognizing those commands.

ive added these into the list - let me know how it behaves.

98% of this is resolved with 2.0.8

With the line for /petattack [@target,harm], [@target,harm] is all white text, instead of green. But that may be related the other issue about some modifiers not being recognised. With my pet on passive, it definitely attacks the target though, and not by means of auto-attacking.

As a side note: it also appears that using a semicolon between modifiers, within the /petautocast commands, no longer works - even for normal macros.

rolling this into #219