🚀 go-pugleaf

(?) My previous answer is gone in digital space. (Can anyone hear me scream?)

GREP to the rescue. Search for

      ,(\d\d\d)




and replace with

      ~S$1




This replaces the commas in "12,345.67" with a fixed space. Next, only periods inbetween two digits should be replaced with a comma, right? Search for

      (\d)\.(\d)




and replace with

      $1,$2




The period in the Search expression needs a backslash escape because it's a special character in GREP searches ("any character").

If you need to run this on multiple documents, store each search-and-replace sequence under a logical name, and search this forum for the little script to chain them automatically.