issues by configuring wacom intuos tablet to have eraser on the stylus button

Hi !
macOS Big Sur 11.2.1
With my wacom intuos S CTL-4100, which has no reverse end on the stylus (that is commonly used as an eraser by clicking with it on the eraser option in gimp) but only two buttons on the stylus side, I can’t assign the eraser to one of the stylus buttons.
In the wacom driver, it is possible to make this setting, so I assigned “eraser” to this stylus button for “Gimp”, but it doesn’t work whereas it works for clip studio paint for instance. In Gimp, as it is possible to click with the reverse end of the stylus on the eraser option, I tried to click on the eraser option while pressing on the stylus button, but it doesn’t work neither.
I searched on the web but I didn’t find anything about a stylus which has no reverse end or about such setting for an intuos tablet.
Of course I could just forget it but it is really cumbersome having to click on the eraser option or to use keyboard shortcut with only one hand each time I want to correct a mistake.
Do you have any ideas ?
Thank you