I did see the issue about an infinite charm belt, and I agree that would be too much. But I think adding a more limited version that can be upgraded would add more depth instead of just letting you unlock infinite forever potions for no inventory cost. Maybe it could be balanced by making the slot unlocking cost something like a nether star? If you have extra nether stars to spend on freeing up 1 inventory slot for a charm you've kinda already beaten everything. And nether stars don't really have much use other than for beacons.

If anyone wants something like this just download the mod curios munchies, it lets you get more curio slots with nether stars pretty much just this suggestion.