As for CastParty, it seems we'd need support for the old version and the new alpha, right? Someone will have to update the code in OnEnable as I'm not using CastParty myself, and I also don't know how to check if its a version with the new or old syntax. I suggest to quote the code in the CastParty forum and let a developer tell you what to change to make it work for both old and new.
The following code should do the trick:
if CastParty_OnClickByUnit then
SquishyCustomClick = CastParty_OnClickByUnit
SquishyCustomClick = CastParty.Event.OnClickByUnit