Solved I think : run this command (shorter than explaining the whole way in control panel)
C:\Windows\System32\rundll32.exe shell32.dll,Control_RunDLL intl.cpl,,0
change language region format to English (I used USA and UK), click onto "Apply"
And Voilà ! Augments work !
You'll notice that Astroneer switched to english language. After having finished playing, you just have to switch back to your own language and click "OK"