Reply To: Change font format with the GREP to change foreign language in document

Depending on how the document was made, you MIGHT? be able to use the normal Find/Change to do this.
If you search using:
Find Format:
Advanced Character Formats
Language: Try the English Options
You might be able to select the english text.

You could then just enter an Italic Character style in the change Format

This worked for me in one document which had P??i words that I needed to italicize. It was a bit crazy, because InDesign had labelled them as ar-SA (arabic!!!)