There is a typo in en_us.json:
"text.autoconfig.dml-refabricated.option.glitchArmor.costs.shulkerFriendly": "Skeleton Friendly Cost",

Originally posted by @qsefthuopq in https://github.com/NathanPB/DeepMobLearning-Refabricated/pull/25#issuecomment-686318256