I have tried using the keyswitch command in the manual on page 26 (G-1) for acro bass 2 to invoke tremolo, but it doesn't work. I noticed that page 37, which is part of the instrument directory, makes no mention of arco bass tremolo.
Am I chasing a wild goose, or does the arco bass actually have functional tremolo on keyswitch G-1?
It does, but probably not the kind you are expecting. The "G" keyswitch doesn't switch to recordings of tremolos, it switches (as in GPO) to programming for playable tremolos. When you play repeated notes on your keyboard controller - pressing down on the key plays one bow stroke and releasing the key plays the alternate bow stroke. So, if you play 8th notes you get 16th note alternating bow strokes. This allows you to play fast enough to simulate a tremolo (even if you are a klutz at the keyboard like me.) This can be further refined in editing by paying close attention to the placement of note starts and stops - plus velocity and mod wheel values. This approach gives the user much more flexibility in performance than "one size fits all" recordings of tremolos. Here's an mp3 example and the MIDI data that created it:
Tip #1: Only the note "on" allows for a sustained note. The note "off" is always short. Use cc21 (length control) to modify the release speed. This can help blend the sawing action - see the MIDI data in the example.
Tip #2: Place the "C" keyswitch before the end of any note you wish to stop normally (like the last note of the example.)
I used the standard, not notation, version of the instrument in this example.
By the way, there will be improvements in this instrument when the K2 update is released - more even response for one.