In addition to the new feature I mentioned above, I have now added an additional feature to my development version of Tabby responsive Tabs which allows a new shortcode attribute of 'target' to be used in the [tabby] shortcode.
Then, when a page containing at least one tabby tab set loads, if the url has a 'target' url parameter equivalent to one of the tabs on a tab set on a page, that tab will be active when the page loads.
If the ticketing plugin allows a page to be specified as a confirmation message, the page should be specified with the '?target=tabx' url parameter to force the correct tab to open. I don't know whether it does work like this, but if not maybe there's a hook that enables a filter to be used to modify the returned url by appending the url parameter to the url?
If you'd like a preview copy of the new version of Tabby Responsive Tabs to try this out and beta test it before it is released, please contact me via the contact form on my site & I'll send you a copy.