In frustration, I contacted Primluce Labs and this was their response:
"I'm sorry but INDI drivers are not developed by us so please send a notification to INDI developers so they can update it and you will be able to use SESTO SENSO 2 with INDI.
We do not suggest to make a firmware downgrade since this could bring to malfunctions."
Are there any other work-arounds or is this a lost cause?