At this time, there isn't an option to revert to the previous Sales Tax Center once you switch over to the automated version.
I understand that we have other users, alongside you that want to have this option available. With that said, we'll be taking note of this.
if you wish to file and pay your sales tax return within QuickBooks Online, take a look at this article: File and pay your sales tax return. It also includes a few steps on what you can do whenever you receive an error while attempting to pay your sales tax return.
I'll be around in case you need help. Place a comment below, and I'll get back to you.