So only issue really was that wife's filing went active earlier than she would have wanted... And husband sensibly decide just to take the opportunity...
No, it sounds like her lawyer essentially agreed to an unfavourable divorce settlement that was still being negotiated. She may have lost out anything from custody of her children to millions of dollars.
I don't know about UK law, but my understanding of the law around here is:
For custody issues, absent extreme circumstances, custody cases don't end until at least the child turns 18. Getting an unfavorable settlement here is a problem, but likely isn't unrecoverable. Typically a judge won't modify a custody arrangement without a change of circumstance; but they do have considerable discretion.
For the financial issues; this is what lawsuits are for. If her law firm does not make her whole on their own, she should hire a legal malpractice attorney who will probably be able to convince them.