Given how the Beat Buddy and Pigtronix Infinity have been perfectly matched for each other, there is one obvious and relatively simple thing that could be added. That’s when you transition between parts, for it to send a CC message to the Infinity.
You would need the ability to select the output MIDI channel on the Beat Buddy so that it matches your Infinity.
From there, when transitioning from Part 1 to Part 2 of a Beat Buddy song, send MIDI CC #25 value 127 to the Infinity (Footswitch 2) that it will begin recording/playing on Loop 2 when Part 2 of the song starts.
Then, when transitioning from Part 2 to Part 1, send MIDI CC #24 value 127 to the Infinity (Footswitch 1) to record/play on Loop 1 when the Beat Buddy goes back to Part 2.
Those are the default MIDI CC numbers for the Infinity. They could be made customizable for other units, or be defeatable in the Menu.