The Bug:
Any labels used for the Quick Play feature (such as "custom", "singleplayer", "multiplayer", "creative", or "survival") are untranslatable.
Steps to Reproduce:
Open the Launcher in the version stated.
Set the language to something that is not English (Settings) and enable experimental features.
Click on the Minecraft: Java Edition tab.
Go to Quick Play look for the strings "custom", "singleplayer", "multiplayer", "creative" or "survival".
→ ❌ Regardless of the language selected, every label remains in English.
Observed Behavior:
All labels are untranslatable.
Expected Behavior:
All labels would be translatable.
Notes:
Attempt to search for the existence of these strings by using this search filter on the official Minecraft Launcher project on Crowdin.
Take note as to whether or not these strings are untranslatable.
The missing strings have been uploaded to Crowdin and thus this issue has been fixed.