Incorrect IP Geolocation

My residential public IPv4 address is incorrectly geolocated ... I have submitted requests to Google and MaxMind to have the IP/Geolocation data base fixed.  ...

That's pretty much all you can do. Comcast/Xfinity assigns your public IP address, but does not control where others think that IP is located. That's done by third parties.

... Is there anything Xfinity can do to help speed up the process?

They can, but they won't. That would cost them a few pennies. The key phrase in https://www.xfinity.com/support/articles/correct-geolocation-data is:

If your geolocation is configured incorrectly, you’ll need to contact either the website you’re experiencing issues on, or the geolocation services themselves.

Whenever it can, Comcast/Xfinity throws the responsibility for fixing things back onto its customers.

@DeltaOne 

I'll add, if I may, to @BruceW 's great info. If you are using a router that has a MAC address cloning feature, you can clone a different MAC address into it. This will force a change of your Comcast assigned WAN / public IP address. No guarantees that the new address won't also have incorrect geo-data as it may be from the same block of IP's. YMMV.

BruceW and EG: thanks for the comments and information.

I have heard back from MaxMind saying the fix will be in the database within two days.  

Late this afternoon my correct local channels are back.  

YouTube TV and What is my IP Address both still show my location as Salisbury, MD (which is wrong).  

maxmind.com, where I submitted the trouble ticket, now shows my correct city and state.

Thank you, @BruceW and @EG for sharing your knowledge with our community on how to have the geolocation data updated and possible workarounds. 

Thank you for creating the post DeltaOne and reaching out to our community for assistance. I see that you were already able to work with MaxMind and that your access for your local networks is back. I'm sorry for that interruption, but happy you were able to have it corrected. If there is anything else that our community can help you with please create a new post and we will be happy to jump in. I hope you have a great weekend and thank you for being with Xfinity! ❤️