Automating multiple global replace in TextEdit?

For language learning, I frequently copy text from a website, paste into TextEdit, and do more than a dozen formatting changes.  Several of these are the same for all languages, so I save the file, do those changes with perl in a script, then open it again for manual edits. **If possible, is there a way to run a script on the contents of a TextEdit window?** A partial (awkward) solution is to save the file without closing the window, in Terminal, run the script and cat the result, then the TextEdit window, Cmnd-A and paste the result into to replace.