MediaWiki-extensions-Score's messages and code specify the use of OGG files. In preparation for the generation of MP3 files, the filetype should not be specified in messages (such as score-oggoverridenotfound) or in the logic. This would make the extension more open with better messaging, and reducing hardcoded values for other audio files to make it more extensible.
Uses of OGG in messages and attributes will be replaced by "audio," while keeping the "ogg" phrasing as a legacy for old scores.
override_ogg should also be allowed to have mp3 files.