I have the GT10 with Yamama THR30 II as well. The page you linked to doesn't work - at all. You can't click on any of the languages. When I use the line 6 updater it says no devices detected.
I find it dumbfounding that in 2021 they have made it *this* difficult to porform a simple update. Whoever runs software for this company should be summarily fired and replaced with someone competent.