This mod MUST HAVE perms for the radius parameter. Without it, it gives any player the ability to crash your server with a single command, which is unacceptable for any plugin. Compounding upon this issue, once the server crashes and this mod is unable to finish its routines, the highlighting effect that shows the chests of matching criteria becomes bugged, and the chests become inaccessible, even as an OP. If this happens to you, note that the highlighting effect is actually using Shulkers. If you swing your weapon around the sides of the chest, you'll hear the shulker deathsound and some shulker shells may drop. Doing this appears to correct the bug.
Get this fixed and you'll get two 5 star ratings and I'll reinstall. This plugin is actually great in concept.