Thanks for the replies, folks.
I never could get the two “samples” working, but I downloaded one more and it DID work, and thus I was able to use it as a sort of template (although I’m still pretty confused - there are some of the files you can easily see where you need to change, but there are also ones that correspond to the same parts but seem entirely made of reddish areas over the whole thing - which obviously doesn’t translate since none of the planes have any red on them at all).
While I could “sort of” do my own it was limited since the way things work text and other areas are often broken up across wing parts. I’m a 3D animator and used to working with 3D Paint programs like 3D Coat which would make the process a LOT easier but I don’t see that these are UV maps per se (or how I would even load and process them). Clearly the best thing would be some sort of “plane editor” as loading these files into Photoshop (even with filters that allow me to work on them) don’t allow 3D painting in the way I’m used to.
But thanks for all the advice - I’m sure there’s something about the others I downloaded that don’t make them work properly but life is WAY too short for me to figure it out (oh, and yes I do own those planes - I have the fullest deluxe version of MSFS you can buy).