The missing key is subpocket.popup.blocked_ender_chest. Maybe the existing popup.subpocket:blocked_ender_chest is intended to be this.

Also, typo of line 52 in en_us.lang : plater <=> player

Hey mentioning to you that I noticed this issue (and also the one where forge keeps thinking that this mod has an update), thanks, would fix it like tomorrow or even a bit later because it was kinda hard for last 2 days with cyberpunk being so good and actual electricity outages at my place, yeah