I have a PC and a swedish keyboard - mine has a comma next to the number pad. I use commas instead of periods when entering decimals in Carrara. I have no problems with Carrara and commas.
I have had several issues with different programs some that have never been resolved (i.e. Photoshop) and of course the evil tilda key…
There can be issues with different international set ups and programs.
It’s kind of hard to know how to fix your problem without knowing what kind of keyboard you have, What are the country settings of your machine, and are you using Mac or PC.
On my PC there is a switch at the bottom right that allows me to go from swedish to english keyboard. Sometimes if that accidentally gets switched it will give me the “wrong” letters/symbols.