About [[MediaWiki:Mwe-upwiz-license-cc-by-sa-3.0-gfdl/en]]
The source text should be corrected. The official name of the license is CC BY-SA 3.0 (only one dash) per [1].
Taking one step back. Is it possible to ferret out all of the messages (source at least) including the literal "CC-BY" since theses would all be wrong as well (I see that a lot of them have been replaced but not all).
You should probably first convince Commons and all the others to convert their templates from hyphen to space? Otherwise we'd only introduce inconsistency.
@Siebrand: thanks
@Nemo: There is a mixture of both being used by various messages so there is already an inconsistency. As for the Commons templates you are correct although these also use Cc-by-3.0 as their official templates (with CC-BY-3.0 as a redirect). A possible first step to right this could be to also create redirects from the official abbreviations to the ones used by Commons.