Regex in item or rule?

I use a say() action to announce the current temperature. Unfortunately the voice reads the point/dot of the float value whereas I want the system to read a comma instead. The announcement should be “21 comma 5”, not “21st 5” as it is currently read.
Where should I change that format? Is the item file the right place for this (there the value is listed as “21.5”) or should it only be changed in the output in the rule file? Or is there a locale setting that maker a regex obsolete in this case?

Quick and dirty - use replace in your say command:

Awesome, thx!