None that scholars are aware of so far, it would appear; though such may well turn up at some point. The question isn't closed. If it were, though, the example you mention wouldn't 'throw open the argument once again' at all.

Perhaps you aren't familiar with the subject of C19 songsters. These typically included a wide range of material drawn from a wide range of sources, new and old, from various countries. The fact that some of the texts in a songster are old or demonstrably from a particular country tells us nothing whatever about any of the other songs, and you would be on very shaky ground indeed trying to draw any conclusions on that basis. To take one example only, you are quite wrong about 'The Rose of Allandale', which is an English song of known authorship (see various discussions here on the subject) and belief or opinion, whether 'humble' or not, is no substitute for knowledge supported by evidence; which is what we have been trying to arrive at here insofar as such a thing is possible.

You may be confusing the points being made in this thread, which concerns the origins of 'Peggy Gordon' and in which no firm conclusions have been reached, with the other thread currently running, which concerns the meaning of one single word found in one single, specifically Nova Scotian, version of the song; and where it has proved necessary several times to re-iterate that in an attempt to keep the discussion at least moderately on-topic.