For some reason "math-visualeditor-mwmathinspector-title" is not on MediaWiki. It exists on Translatewiki: https://translatewiki.net/wiki/MediaWiki:Math-visualeditor-mwmathinspector-title/en
Topic on Help talk:VisualEditor/User guide
I've finally found the new version, and added it. It's been a long while since this was updated.