Draconic Endshelf: 3
Pearlescent Endshelf: 5
Melonshelf: 4

Stats: Eterna 50/50, Quanta 12.50% , Arcana 37.50% OK - exactly upper limit but no more than it)
Result: Infusion not available
Expected result: Infusion available (Arcana at least 32.5, no more than 37.5: its no more but equal).
Please fix check for value range at edge

This is because of the enchantability bonus from the charm itself (every item is providing a base value of 1 due to a global change).

I've reduced it back to zero for the charm. I may undo this change entirely in the future, as it is also what allows every item to receive Soulbound when a mod that adds it is present.