VE-635: Keyboard shortcut for source editor

https://wikia-inc.atlassian.net/browse/VE-635
Ok, so here it is hardcoded that "[" is shortcut (with prefix) for source mode, but in the place where the help is generated it uses MW message: 'wikia-visualeditor-accesskey-wikiasourcemode' - which could be overwritten locally and then it gets out of sync.
I'm not sure why to usage message in first place? Is it something that is meant to work different in different languages?