This doesn’t answer your questions directly but have a look at GameDev.tv. They use a massive number of tags to manage their online courses (
) but it seems to be working quite well at a glance.
Are there any specific issues or pain points that we can fix here? I can see that a few items you requested in '17 on It's Time We Talked About Tags are now supported. For example, we now have coloured / icon tags through the Tag icons component 