So it’s been modified to operate outside the factory parameters and you wan a cassette that holds up better?
I would try the Microshift Advent 1x9 drivetrain.
It’s inexpensive, you have an 11-42 cassette, it’s super strong, shifts better than drivetrains that cost 5x as much and the cassette is super cheap to replace
It also is pretty unaffected by dirt and if it gets knocked out of alignment it will still shift through all the gears.
I have run it on my Kenevo and on my 2020 S-Works.
They just released a 10-speed version that will give you almost the same range as a 12-speed