While this is not a TapaTalk replacement; Google Chrome has an extension that supports XenForo forums. It will monitor the forums you go to in Chrome that run on XF and display an alert when there is an alert on that particular forum.
If you want to try it out go to the Google Apps Store, search XenForo, and select Forum Alerts. Then allow it to install the extension. Restart Chrome and it should be running.
If you want to try it out go to the Google Apps Store, search XenForo, and select Forum Alerts. Then allow it to install the extension. Restart Chrome and it should be running.