If you rename a wind charm in an anvil you can no longer register a position. They work fine if you register the position first and then rename them.

In my idea, when crafting wind charm alone, registered information disappears.
It had been once implemented, because of received the request of "Wind Charm hardcore mode", its function has disappeared for difficulty increases.

And if necessary, I would add a configuration item to revive this feature.
I'll add it to the time of the next update.

I'm not sure you understood me correctly.
I like that the wind charm cannot be cleared as a limiting factor.
The issue is when I rename it:
http://imgur.com/o8NmCHI
If I do it as shown in the window, the charm is broken, I cannot register a position any more.
If I register the position first (before renaming), it works.

The name of Items and the warp information of Wind Charm, both are managed by NBT tag.
Because many MOD is using NBT, in order to avoid interference, warp information are registered only when using a charm which does not have a NBT.

At the time of the next update, for changing this specification, NBT tag warp information will be changed.
Charm that already has a warp information will be unavailable.
Although remedy is added, re-registration of warp information must be required.