J.S. from Sweden confirms that the Trio Medieval/Glitterind tune for "Rolandskvadet" is a popular, common tune to sing in Norway. He provided fifty Norweigan variants on the lyrics, as well as a link to this page. Of the contents of that, he says:
[I]n the 1840s, Norwegian folk song collector Magnus Brostrup Landstad found 27 stanzas of the Roland song in a handwritten songbook of Laurantz Groven from ca 1800, but there were pages missing in that book, so that the first "complete reconstruction" of the Norwegian version was published in 1890 by Moltke Moe who "reconstructed" it by filling the gaps with his own poetry and changing the order of stanzas to make it more congruent with the Karlamagnús saga. Moe's lyrics are those which are most often sung in Norway today.
The same website says that there exists only one tune from Norway to this ballad which was collected by Hans Seeberg and Olea Crøger in the 1840s from a singer in Seljord in the Telemark region. However, it is seldom used; the Norwegians mostly sing the ballad to a Faroese dance melody which was introduced in 1934 by Klara Semb in her songdance circles. Since the Faroese ballads usually have much longer refrains than the Norwegian ones, the Norwegian lyrics were not long enough to fill out the melody, and so Hulda Garborg translated the Faroese refrain to Norwegian.
Which Faroese song? J.S. points to this Danish collection of tunes, published in 1908. Songs 54a-d on pages 124-125 are all variants of the Faroese "The Battle of Roncevaux," and their refrain is exactly the one used in the popular Norwegian version of the song. And here's a YouTube of the Faroese dancing that dance.
It's... doesn't sound quite the same, except the cadence on the refrain, but when I look at the transcribed sheet music, I definitely see the very strong similarities.
Trying to find that 1840s tune, I turned up some field notes preserved in... a national library? I don't see this ballad on those leaves, but the library assigns it the title "Ludvig Mathias Lindeman: [Folkemelodier II]. 'Melodier fra Thelemarkeni." Seeberg and Crøger are recognized as 'Creators' but Lindeman is the 'collector.'
Lindeman! We've seen him around here before. "Melodies from Telemark." Another page of music, with the Ramund that confounded me before. Searching for Lindeman's book brings me back to the same collection I examined before, and could not find any Roland in. Either the referenced website is in error, and there is no tune for Roland in Lindeman's collection, or I'm just not recognizing it. (Or there's another collection, possibly entitled "Melodies from Telemark," that's not available digitally.)
Anyway! I think that runs the song's provenance pretty much into the ground. So what do I do with it?
I'd be lying if I tried to pass it off as "Anglo-Saxon." It's Continental, in subject matter and in poetic form.
The tune is as neo-medieval as anything I'd come up with myself. It's got a narrow melodic range (a fifth) in D-Dorian, and has a simple contour with lots of flat spots. Guido d'Arezzo would approve of the construction, I think. And the tune is catchy. The subject matter is period.
I think it'll make a good performance, albeit an "SCA appropriate" rather than a period one. But despite its range fitting exactly onto my lyre, I think it should be done a capella or else with harp. I'll think that over, because of how tempting it is to do epic material with an instrument that probably accompanied epics, but the rhyming form is just plain later than the instrument.