Ooh! I had forgotten about this post until I saw the followup message.
The good news is, you're in luck!
While trying to figure this out, I contacted the developer of LaunchControl, because it was not working in launchd either.
He took a look at the code, and found a bug in the way that icalBuddy was doing something. Apparently the bug didn't show up except in one of these situations like Keyboard Maestro, launchd, or TextBar.
He sent me a fixed version, which I am happy to share with y'all:
icalBuddyFixed.zip (54.1 KB)
I sent the fix to the current maintainer of icalBuddy, with the hopes that it would be integrated into the official release, but so far I have not heard anything back from him.
However, I have been using this without problem, and I hope it will work for you too.