I have the three files open in geany right now. But I haven’t seen where to actually do something like change “fits/FITS” to “ARW”. Can you give a hint as to what to modify?
As far as the fading daylight goes, I’d be happy enough to adjust each layer using Exposure Comp or Levels to make the histograms more or less match. This doesn’t need to be anywhere near exact for this particular stack of raw files.