I took a trailhead module to maintain a Salesforce certification, but I don't know for sure that the certification is "maintained". I linked my WebAccessor account with Trailhead before completing the maintenance module, but I haven't received any confirmation my certification will still be current as of tomorrow. Today is the deadline for maintaining the certification. My certification isn't found I try to verify it using my name or email address.
Try the above link. You can search by your name or email and it should tell you what certs are live for you.
You can login to Webassesor and have a look at your list of Completed Exams. The maintenance exams done on Trailhead will show up there eventually:
As an additional note to using https://trailhead.salesforce.com/credentials/verification to verify your credentials: If you're using the 'Verify a Salesforce Certified Professional' to search on your full name or email address, you need to optin for this verification in your Webassessor profile before anything will show up.
I think the 'Certification Holders: Check your Status' doesn't require this, but you of course need to use the email address that you use for your Webassessor account.