Greetings,
I ran into a small issue and didn't find any mention of it in the documentation or the forum, so I hope this helps someone.
If you call the acplPublishExecute() function without having used the PUBLISH command, publishing will fail with an empty error in the log.
It appears that the PUBLISH command will load the AcPublish.arx module as needed, but acplPublishExecute() will not, so make sure to load it yourself.