Enchantment table tuning

The enchantment table system could look like this: Instead of 15 bookshelves require 5 chiseled bookshelves. There are over 30 unique enchantments in the game. Require 12 unique enchantments of any level to be placed on the shelves before the enchanting table works. You're then creating a pool of enchantments to apply to a new book. The more unique enchants added to the shelves increases luck. Luck influences the instance of bonus enchantments as well as a small chance to upgrade the enchantment level. Example: Early/mid game you get a table together with 5 chiseled bookshelves. You explore and find a few books in structures, maybe some from fishing, and maybe from raids or trading. You finally get enough books to get 12 different enchantments on your shelves. Most of these are not Max level but that's okay for a start.  You use the table trying to get copies for your gear and BAM that protection 2 book on the shelf just yielded a protection 3 book! What luck! You add it to your shelves and now the lowest protection enchantment you'll get is 3. Slowly, with luck and lapis, you've maxed every enchantment on your shelves.  If you take the time to gather many unique enchantments the leveling up of books will happen much faster. Once you've put the work in, you could reduce the number of enchantments on the shelf and narrow down the random element (at the risk of less bonus enchants). You can "tune the table" in an effort to get more of what you want and less of what you don't