iOS 10 broke my decimal separators, any way to change them back?
Yes, please have a look at Settings > General > Language &amp; Region.

After "Preferred Language Order" you see a setting for "Region". Change it to your preferred setting.

If it is already set to your correct region setting, set it to another region and then back to your preferred region.

Let me know if this works for you.

edit:
Make sure to check the "Region Format Example" field. It displays how the decimal separator will look like.