Thank you for continued care for 1.12.2.

I would love to see the ability to add custom crates and keys, Not only would this make me as a modpack creator, be able to add more content, But will also greatly increase your mods spectrum of possible content. I understand that this suggestion might not be worth doing for 1.12.2 but would still be sick to see for newer versions

I don't think this is doable.