Can JotForm sync with Google Docs or any other Excel format?

Or is its primary capability to sync with email and create PDFs?

You can integrate your form to Google Spreadsheet: https://www.jotform.com/help/228-How-to-Integrate-Form-with-Google-Spreadsheet.

You can also export your form submissions into an excel format: https://www.jotform.com/help/73-How-to-Download-Form-Submissions-as-Excel-CSV-PDF. 

Hi there --
According to the respondents in those threads, it looks like a lot of
people had issues with the Google Docs integration -- is your impression
that this is less buggy / more trustworthy now?
Let me know & thanks!
Melissa
...

Yes, Google Spreadsheet is stable now. Those are comments/feedbacks way back a year/months ago. But if there are issues, let us know and we'd be happy to submit it to our developers.