All three girls were in their first year in juniors and Karen clearly suffered from injuries. Give them time. Better they get the experience now.
Karen had problems rotating her jumps when she was fully healthy. I don't think you can blame it all on her injury.
The problem is the US lost a lot of JGP slots with this result. So, many young American skaters are not going to get the opportunity to compete internationally next season. The JGP field was already crowded, so with the reduced number of spots, maybe the USFS will have to start sending some of the girls who have been on the JGP for a couple of seasons to Senior Bs.