I do not think that is possible with InDesign’s GREP.
However, if you had a lot of this text that required searching, it might be worth the time to export as InDesign Tagged Text. When you do that and open the tagged text in a text editor, you would see something like this:

<ParaStyle:NormalParagraphStyle><cTypeface:Italic>Natiunt am eumenet idus adi dolora sum harcimus recum aceribus ad quid endamet fugia sin custiae ctibearum sunt aut faces aut<cTypeface:><0x00E9><cTypeface:Italic>nis apienimus maxim voluptia voluptatate prat lita dolorernam que sit a que laborem necaboribus magnatur aut ut utemporem as eos que con elliqui dusdam que nonsequatat.

From there, you could search for places where the typeface is changing at the accented e (which is what that unicode 0x00E9 thing is in the middle of the paragraph).

This is pretty geeky, but it can work, I think.

Yes, GREP is incredible. You can learn more here: https://creativepro.com/grep

This isn’t really what you’re trying to do, but does it help at all?
https://creativepro.com/continued-heading-table.php

You want to make sure that you’re actually converting those two rows to header rows.

We also run an informal InDesign wishlist here:
https://indesign.uservoice.com/forums/114445-adobe-indesign-wishlist/filters/top

I just copied your message into InDesign and spell-checked it and all those hyphenated words were spelled correctly for me. I wonder why they’re showing up as incorrect for you? Maybe the Language applied to the text in the Character panel?

Oh, dang, you’re right! It is hiding inside content options. My mistake. Thanks. Not sure how you’d put all that together. Perhaps Loic knows a way to make the script do it.

I don’t think there’s any way to do that. Maybe a custom script.