I don't know if this is dynamic enough or not efficient enough but I got this to work with 3 actions:
Parse text action:
Regular Expression: (,)\d
That returns Match:
Then just use Reverse text to that %Match%
Then Replace the original value with regular expression:
Regular Expression: (,)(?<=\d,)\d
Output:
If that works you should try it with different types of values that you might get in the flow.
