Which characters in the story Miss Tempy's Watchers are round, flat, dynamic, or static?

There are only three characters in Sarah Orne Jowett's short story "Miss Tempy's Watchers," and they are Temperance Dent (Miss Tempy) and her two longtime friends, Mrs. Crowe and Sarah Ann Binson.
Miss Tempy is a static character whose characterization is somewhat flat. She does not grow and change over the course of the story, either in reality (because she is deceased) or in her friends' recollections of her. Her personality is defined by gentleness, kindness, and generosity, which is confirmed by each anecdote her friends share. There are no complexities to Miss Tempy's character: she was simply a good woman who was well-loved by her community.
Mrs. Crowe is a dynamic character whose characterization is quite round. She changes over the course of the story, letting down her guard and revealing her faults and fears, which show her to be a complex person. She appears friendly to others in the community, and holds high social status due to her wealth, but she admits that she is not as good or kind as people imagine she is:

"It ain't so easy for me to give as it is for some," she said simply, but with an effort which was made possible only by the occasion. "I should like to say, while Tempy is laying here yet in her own house, that she has been a constant lesson to me. Folks are too kind, and shame me with thanks for what I do. I ain't such a generous woman as poor Tempy was, for all she had nothin' to do with, as one may say."

Mrs. Crowe is emboldened by the intimate circumstances of the wake to confess that she is not the person she wishes she was. She confides to Sarah Ann that she is "humbled to the dust" by Tempy's example, and will strive to be more like her henceforth. Mrs. Crowe and Sarah Ann come from different sides of their small community, and Mrs. Crowe's shy admission does much to bridge the divide between them:

Sarah Binson was much moved at this confession, and was even pained and touched by the unexpected humility.

Mrs. Crowe must also face up to her fear of death when she and Sarah Ann go upstairs to look in on Miss Tempy's body where it lies in repose. She finds viewing the body very difficult, but she goes through with it nevertheless, and afterwards, is able to speak about death and Miss Tempy's dying much more freely than she was at first. When the story opens, Mrs. Crowe says:

"It is strange to set here without her, but I can't make it clear that she has gone. I feel as if she had got easy and dropped off to sleep, and I'm more scared about waking her up than knowing any other feeling."

After viewing Miss Tempy's body, Mrs. Crowe is able to accept her friend's death, and to remark that "Tempy aged all of a sudden," and there were indications of her declining health for a few years before her passing. She is able to speak about Tempy in the past tense, and she feels a kinship with Sarah Ann for having shared that difficult moment with her.
Sarah Ann Binson is less dynamic than Mrs. Crowe, for the changes within her are subtler, but she too is a very round character. While her personality is described as "sharp and anxious" and her life seems hard-driven and unglamorous, she is actually a kind person who finds great happiness in her lot:

However pleasureless her life appeared to outward view, it was brimful of pleasure to herself.

Sarah Ann is at first inclined to regard Mrs. Crowe with a bit of amusement, occasioned by the social distance between them and their overall lack of familiarity with each other. However, she comes to trust the other woman and to feel affection towards her as Mrs. Crowe reveals her vulnerabilities. The barriers of status and public personas break down as the women keep watch over their deceased friend, and Sarah Ann learns that Mrs. Crowe is a rather lonely person who hopes to become a better version of herself. Sarah Ann is prickly, but she relaxes her judgement of Mrs. Crowe and works in their conversation to bring the two of them closer. At an awkward moment when a touchy subject has arisen, Sarah Ann tactfully moves the conversation along:

. . . and with this modest avowal the critical moment passed when there might have been an improper discussion.

Later, when the women go upstairs to look in on Miss Tempy's body, Sarah Ann pities Mrs. Crowe's nervousness:

Mrs. Crowe gave a little sigh, and Sister Binson’s quick sympathies were stirred toward this other old friend . . . like the comforter she truly was.

Although Sarah Ann does not need to confess any particular faults, as Mrs. Crowe does, she also grows in the story, by allowing this mutual friend of Miss Tempy's into her heart. By the time the sun rises the following morning, the two women are good friends.