It seems they have completely switched to the Latin alphabet now (the language is being actively standardised) so I don't think using a Runic alphabet for the modern version of the language makes sense. For an eventual Wikisource, though, the Runic alphabet has valid use.
The code issue here is an interesting one. In the first request, 10 years ago, they used the code "dlc", which was included in the draft of ISO 639-3, but not in the final version. I don't have any sources for this (it's a long time ago), but what I heard then was that Elfdalian and Scanian (skånska, code scy) were supposed to be in ISO 639-3, but were not included because the Swedish authorities would refuse to ratify (/accept?) ISO 639-3, ostensibly for political reasons. Now that it has a code, however, I'm more than happy to give this eligible status. The fact that it doesn't (yet) have an Ethnologue page doesn't matter at all.
I'll contact WMSE to see if they would be interested in supporting this language edition. As far as I can tell, there are still no native speakers who have signed up for the proposal.