Problem: The Score extension is not particularly easy to use due to not having a graphical input option, and has not been updated in almost four years. Furthermore, the rendering is pixelated and PNG instead of SVG; and the image is hard to resize (a paper size has to be specified) and align (a div has to be made to align it and the audio player to anything). In addition, the double bass and possibly some other instruments are not playable. These are all limiting factors in its use, and partly as a result it is only used on 396 English Wikipedia articles and 873 English Wikisource pages, when it could be used to a much greater extent than is currently possible or desired. It is indisputably inferior to the MuseScore.com web app (closed source based on open-source software), which does not have any of the aforementioned problems, has an animated and scrolling score (entirely SVG), and was probably written by a few interns and MuseScore's permanent staff of three people.
Who would benefit: Wikipedia and Wikisource editors, and readers of music-related articles
Proposed solution: Any or all of: improving the extension so that the output is an SVG file and can be easily resized and aligned; adding an OCR helper for printed and engraved scores like the DJVU reader on Wikisource; allowing MIDI/MusicXML/MuseScore files from Commons to be read by the extension; adding a visual editing function; replacing the current extension with MuseScore-based renderer/playback.