Should she have gotten rid of her coach who helped her achieve what she was able to or continue to work with the guy?
If I understand this correctly, Nigel Sears (her coach at Wimbledon) and Andrew Richardson (her coach at the US Open) were only temporary arrangements, apparently.
Andrew Richardson doesn't/didn't want to be her coach full-time as he wants to stay in the UK and coach his own son, who is one for the future apparently.
Jeremey Bates was temporarily brought in for Indian Wells, but he is committed to Katie Boulter (asaik).
She's had trials with a couple of other coaches since, with Johanna Konta's ex coach being one of them (can't remember his name off the top of my head) but the trials don't seem to have worked out for whatever reason.
I think she shouldn't have taken her foot off the gas for as long as she did after winning the US Open. Take a week off maybe but get straight back to competitive matches as soon as possible. After the US Open win she probably did too much media stuff and Raducanu herself saying that she needed to 'find my tennis' said it all, imo.
One thing I have read in a few places now and heard commentators say is that her father is the one that calls the shots i.e. coaches need to be prepared to work with him as well, which is apparently not easy.
I think she's possibly been badly advised so far, that would be my guess, but just have to see what happens next.
Edit: Just having a quick read about and some media sites are saying that Andrew Richardson was 'axed' but I don't think that's correct. I remember Mark Petchey and Tim Henman (they're all mates) saying at the time that it was only ever going to be a short-term thing.