The anvil will show the rank. After mod optimization though, you don't actually need that much experience. But you have to reach the corresponding level to operate.

That is intended, unless I misunderstand what you are saying.
The anvil will show the level requirement (which is just the level cost in vanilla Minecraft).
When paying, it will be transformed into an XP cost, which is generally much lower than the level cost.

In other words: This mod won't allow you to enchant any items earlier than usual, it essentially just "refunds" the usual XP loss due to your high player level.

ok