Not every Switch game requires ace2-fmt.bin . The file is typically needed for titles that rely heavily on dynamic audio modulation, high-fidelity voice tracks, or real-time audio effects.
As Nintendo releases new Switch games, the ACE2 audio engine receives minor updates. Newer games (post-2023) may require a newer version of ace2-fmt.bin than what is available in firmware version 15.0.0. ace2-fmt.bin
The "ace2" prefix identifies it as part of the of flashcarts, which are popular, affordable devices used to play homebrew applications and backups on Nintendo handhelds. The ".bin" extension indicates a binary file, often containing compiled code that the console's processor executes directly during the boot phase. Not every Switch game requires ace2-fmt