There is no requirement to donate divorce settlement to charity to somehow prove domestic abuse.
No, there isn't. That is not what was argued. Depp's lawyers were arguing that this shows Heard lying in her evidence to court and, according to them, going to considerable lengths to try and cover up the lie. Whilst it does, as you say, go to the claim that she was a gold digger, it also goes to her general credibility, which appears to be the main point Depp's lawyers wanted to make.
I'm surprised the judge has made such silly errors and not jade this water tight!
The fact Depp's lawyers are claiming he made these errors does not mean he did, in fact, make such errors. That is for the full Appeal Court to decide if the judge gives Depp leave to appeal.
The odds are against Depp being granted leave to appeal. If he is granted leave, the odds will be against him winning his appeal.