Just wanted to let you know that progress bar has been fixed. Cheers!

EDIT: Thanks for the updates, I just looked into the issues you mentioned and sadly I cannot reproduce them. I even tried setting my YT language and region to JP and I verified it on the same video you linked but nothing breaks. If it requires some specific steps for the bug to occur then let me know. Also check if some other extensions or userscripts aren't interfering with YouTube Redux. It also appears that recently YouTube got some updates that introduced various bugs by itself so there could be stuff broken that's not related to the extension. Anyway I'll investigate further to see what could cause the long loading times since 1.3.5.

Unfortunately I'm not getting any notifications about review edits so I missed that - feel free to contact me via email or reddit thread that's linked on the extension page.