All the released firmware versions are available. The latest VemsTune is backward compatible and is what should be used.
As far as upgrading firmware from 1.0.7x to 1.2.42... there are SO MANY feature additions and code changes in that span, it would need a re-tune at the very least. With that big of a jump you can think of it as a whole new ECU upgrade.
You can go through the FirmwareChanges:
https://www.vems.hu/wiki/index.php?page=GenBoard%2FUnderDevelopment%2FFirmwareChanges which is standard best practice when upgrading firmware and read from installed firmware version to what you want to upgrade to, and those features will need to be tuned or at least looked at. The list is massive between 1.0.7x and 1.2.42 or even 1.2.31.
You can easily keep 1.0.7x and tune it for the changes. Just download the newest VemsTune and connect to the ECU, adjust.