You can perform the alternations at any tempo, it's just about the gaps between the notes, in a slower tempo the gaps may become to large therefor the player triggers starting notes (where two alternating variations are available). Just take care about the gaps between the notes, minimize them if necessary, and you will trigger the "performance repetitions" (8 variations).
best
Herb
Hi Herb!
I think it would be VERY helpful if in the manual there was some coverage of how to get Synchron how to "behave" based on the MIDI notes themselves. I remember a past thread where I had asked if legato behavior was affected by touching vs overlap vs long overlap notes. Or maybe a video tutorial?