How can I change the number formats so that commas are a decimal separators? So 1,5 is one and a half (the system now replaces it with 15)
Your best option is likely to use a regex pattern under the question’s validation tab:
SurveyGizmo offers a handful of built in Regex options as noted above, but it looks like the one you are looking for is not one of the provided ones.
There are a number of online resources that can help you track down the regex code that you would need for your situation. I did a quick google search and came up with these results:
Once you have a code that you feel is the right one, you can test it here:
I hope this helps!