Hey, thanks for work on this very cool mod!
One suggestion that came to my mind -- there's valuable information in the data the mod is storing, which is the name and location of the container for a given item. If the container storing the item is not in visual range, the current solution of highlighting them in the world doesn't solve the actual problem :). A simple solution could be to show the coordinates & item name (handy in the case of named shulkers) e.g. on hover (maybe with a modifier like Shift key).
The other thing I'm using the JSON storage for is finding lost shulkers (shulkers I've placed somewhere and forgot to pick up while on a trip). It'd be awesome if this could be somehow also enabled via the in-game UI. (Container overview with all their locations & names?)