But did Mrs. Johnson's personality change? I agree that:
one could argue that there was a natural change in her attitudes over time
but wasn't she the same picky, outspoken, narrow-minded, and amusing woman in 1970 as she was in 1966? It's true that her relationship with the family went from adversarial to that of a devoted employee, but when when we first met her she was just as fiercely devoted to Bill Malloy. Unfortunately, we didn't see much of the character post-1897 (only appearing a handful of times, and half of those were in 1995) anyway.
I think we have to discount older Carolyn's story about Mrs. J brushing her hair when she was a child as the ramblings of someone who doesn't have a firm grasp of reality.
I think she did mellow over time. When we first met her, she was almost nasty and hell-bent on revenge. Also, there was that scene in the diner where [spoiler]Maggie served her a roast beef sandwich and Mrs. J. kept complaining about the mayonnaise, bragging how she'd always made her own, and even going so far as to smell the sandwich![/spoiler] As time went on, she lost that crabbiness, although one certainly couldn't accuse her of being Mrs. Sweetness and Light -- LOL.
As for Carolyn's musings as a madwoman, it's possible she referred to herself as a child having her hair brushed by Mrs. J. simply because she was no longer that wild teenager we first encounter during the early days of the show, which is when Mrs. J. came into the picture.