So a bunch of Magatama's appeared in Kaguya's list, that all include " ***GARGOYLE_STUFF***crystal " followed by a number in brackets and then a bunch of 0s.

I am wondering if these are placeholders for a future event, as they are all labeled this way... but they shouldn't be accessable. It's not possible to purchase these since it's impossible to get that Gargoyle_Stuff. Anyone else can confirm if they have this "Stuff" available at their Magatama Idol Kaguya?

It's future content with placeholder names. Just ignore them.