It always bugged me that they simply refer to her as "Lady". And then at about two in the morning when I was looking at my last beer, I realized: After they leave the North, they're no longer speaking the same language, so "Lady" would sound like a normal name to everyone they met, and not sound like the title that it started as. It only took about three months for me to figure it out.
It also helps that they drop the "The" after leaving the North. In the North she is "The Lady", her title. In the South she is just "Lady", a name.
Actually, it's not a fridge trope, since it is explicitely described in the book.
Croaker's status as an "Old Man" doesn't make sense at first. By Croaker's own reckoning, he is (biologically) about fifty-six at the start of Soldiers Live, but Murgen was calling him "the Old Man" as early as Bleak Seasons, when he would have only been in his late 40s. The thing that has to be remembered is that Croaker has seen and done an awful lot in his fifty-six years, both from the physical and mental sense. In an age where horseback is the fastest means of conveyance, he covered almost 8000 miles in his time as Annalist alone. He spent between six and nine years as Captain, during which he was also the military dictator of Taglios, an intensely stressful position. By the end of Soldiers Live, he probably looks more like his 71 chronological years than his biological 56.