Thanks for answering a specific question I had in mind--how to use the kr tag. I write on Korea (from time to time). Wasn't sure whether or not to use the #kr tag, or a #korea tag. Now I know. If I can't write in Korean, I shouldn't use that tag. Another tag also clearly defined (and misused by me, I'm afraid), #photography. Didn't realize #photo was more appropriate for a blog featuring vivid photos that are not original (but credited). As a relatively new user, I'd like to observe the etiquette of the platform. You've made that easier to do. I write on a wide variety of subjects--have wide-ranging interests, although history, language, literature and science are likely to attract me more than cryptocurrency or gaming :). Without being wedded to a specific niche or community, I can easily stumble into a faux pas. This guide will help me to avoid that.
There is no clear distinction between country tags and language tags. The distinction should be up to the tag users themselves. If you write about Korea using either tag but nobody objects, you should be OK. I frequently write about China or Chinese topics (mostly language, which is my academic specialty), but nobody has ever objected. The worse tag users can do is to not read your content, i.e. ignore you completely :-((