A few suggestions that may help:

1- Make sure the name on your GitHub profile exactly matches the legal name shown on the CHSI report (including the order of your surname and given name if required).
2- If your application is still pending, avoid submitting multiple new applications, as that can sometimes reset the review process.
Keep all follow-up communication in the same support thread so the reviewer has the complete history.
3- Since your university doesn't issue a .edu email, the official CHSI enrollment report is generally the appropriate document for manual verification.

At this point, a manual review by GitHub Support is likely required. Hopefully they'll be able to verify the CHSI document and update your Student Developer Pack application.

Best of luck—I hope your application gets approved soon!