Sound events not defined in "music_definitions.json", preventing playback in corresponding biomes

The following three sound events —

• music.overworld.frozen_peaks

• music.overworld.meadow

• music.overworld.swamp_music

are not defined in music_definitions.json, and therefore do not play in their respective biomes (frozen_peaks, meadow, and swamp).

Instead, the biomes still use the old events:

• music.game.frozen_peaks

• music.game.meadow

• music.game.swamp_music

This raises a question: if new sound events have been introduced, why are the old ones still in use? Shouldn't the new events be properly registered and replace the old ones?