I googled “French keyboard” and check a bunch of images. All of them have alt or ⌥, and all of them have Windows or Mac. What does your keyboard look like?
We have all the special keys, but we must use “shitft” to access the numbers on the top row.
So, “4” is “Shift+4” and Alt+shift+4 is translating as Alt+4 if you presse the three keys on french (and many others) keyboards
The forums are public. All conversations here are in public (unless of course they are in PMs) and are part of the public record.
If this is indeed a problem with keyboards that produce alternative key scan codes for multiple languages other than English, then there is a strong possibility that a) other people might also be seeing this problem and b) some of them might indeed be interested in a workaround until such time as Scrivener has a fix for the issue.
It is a “bug hunt forum”, and you are going quite far from the initial subject.
There are “help” forums and discussions, here or on FB, etc.
But ok, lets do it.
This problem is a localisation problem. It has been reported already in 1.9 and in beta. It needed to be reported in V3.
Workarounds are already been explained many times in many places. So, ok, we can do it again here, but if I was the moderator I would surely remove it as it is a BUG HUNT place. ie the place where you report the bugs. Not the Technical support (viewforum.php?f=30) thread.
Speaking as a moderator, we usually aren’t that strict about it. It is in fact considered polite around here to share a workaround when someone posts a bug, so that they can get back to work or find a way to use the software despite it. If you don’t need the tip, then it is fine to just leave a short thank you, or even leave it be without response, and wait for an official reply.
The issue with AZERTY keyboard layout and the need to use Shift to access numerals being in conflict with the built-in Styles shortcut is a known problem, and was assigned ticket #4877, February 13th, 2021, by myself. It has not seen activity yet (there have been many high priority things between getting to it, in this past month), but I’m sure they will come up with a solution.