But no; it's much more definite than that, in every sense. Paul has already been told that the Lord is taking him to Rome (Acts 23:11) - the only thing not specified was the how and why of the way in which that journey would come about. The purpose for going was as clear as day:
As you have testified about me in Jerusalem, so you must also testify in Rome (Acts 23:11)
So Paul's appeal to Caesar is neither impetuous nor desperate; it arises in the context of the Lord's clear direction and decision to send his apostle to the heart of the empire. And the forcing of Festus' hand is not a matter for regret; it is simply the Lord's time and place for enacting his plan to send Paul to Rome.
I'd never seen it that way before. I do now.