You didn’t have the Colors problem in French, and so long as you stay on Monterey I think you won’t see that. Which should mean you can switch back to using French.
Even so, being in English shouldn’t impose the US delimiter characters. I will take a look at that.
In Ventura you can change the number format without changing the language via an item in the macOS settings. I tried this and successfully flipped back and forth between comma and period for the decimal separator. SketchUp followed correctly. Not at my computer now, so I can’t remember the exact setting, but I think it is under General and maybe localization ?