My best guess is that G.W. Lee did not die in the Cherokee Nation. The Unit was at Ft Gibson and there was probably bad communication. He did die at Jackson, MS. I have seen his grave in the cemetery at Jackson. His unit was near Corinth in horrible conditions. They shipped them by rail when they were very sick to Jackson. I could not find the 3rd G.W.Lee you mentioned at Fold3.
I am working on a detailed account for each soldier of the 6th Texas at this time and will do the 9th next. I do appreciate your research.