Update.
I saw my sister in person for the first time in a year over the weekend.
Her kids' COVID cases I wouldn't call "mild" as there were significant symptoms, but they lasted only about a week with a long recovery time- still somewhat weak.
My sister was down for a good 30+ days. She had a high fever, then it cleared, then 2 days later, it was back for several days, then cleared, then came back for several days again. She lost a lot of weight- and she's 6'2" and was under 150# to begin with. However, she is doing well now, but still only has energy for 3 or 4 hours of activity a day (and she is quite athletic normally).
It's very good news, but the recovery is still ongoing.
My Mom never got it, nor did my brother-in-law, at least, no symptoms.
Good to hear, they are on my prayer list...