Happy to hear that your upgrade of your site went well
One little thing I note while reviewing all files: the version strings are not all set to 7.7.0. Most of the files stay at 7.6.2 or older.
The 7.6.x version descriptors were intentionally left in the TEMPLATE comment headers that have had zero changes to them for the release, with the idea that doing so would make it easier for moders to reference back to a script template change affecting their customization.
All of the PHP scripts and CSS were touched/reformatted for UBB.threads 7.7.0, so they get bumped up the current version -- even if their change was purely astatic.
tl;dr, If files get changed, they get a their respective current version comment updated. Unchanged files remain with the version comment the last time they were changed.
