RABBITICOL No idea. I don’t think authors can add any more tags than its current limit. In the past, you needed 10 people to add a tag, and you could have any number of different tags.
Now that they changed the system to where only authors can tag, the old tags that got at least 10 people tagging them each got translated into the new system. I recently-ish updated my book’s tags, so even if just added a space between two words (because previously spaces weren’t allowed), it made that a new tag and reset the “likes” (formerly the number of people that added that specific tag in the past) to zero.
Right now, whatever tags an author adds to their book’s information, it shows up on the book page itself. But for the search results or browsing pages, only 2-3 (depending on layout) of the most liked tags will show up on there.