The language is part of the song.

Texture, if it means anything, is a matter of interpretation.

Rhythm comes in more than one form. There is no reason not to take (say) "The Wild Mountain Thyme" and do it in 4/4 in stead of the more common 3/4.

But the regionality of the song is part of its 1954 definition legitimacy of currency in a community. Dialect (and similar) words and phrases should therefore be preserved but copying accent is condescension. Clarity of articulation may be a barred by the currency of the song as a folk song and while I would not usually do an Appalachian song (since I am not Appalachian) except to return a preservation to its English roots (well, environment, anyway) I would not dream of rendering songs in RP save to the extent that it was my natural way of articulation.

Many a tale hangs by what sort of accompaniment adds to or detracts from a folk song.

And some operatic renditions of say "Barb'ra Ellen" (or "Allen") are amongst the most disgusting things I have ever heard.