At that price any copyright lawyer will be happy to deal with the paperwork. You were making 2000/month, so the infringement is taking money away. For a share of that it is easy to register the copyright and then send the proper letters. Probably this will settle out of court where apple pays your lawyer from fund the developer would have got and then removes the app. you get nothing directly from the lawyer except that next months all your sales come back to you since there isn't the competitor.
It is, but the US and the EU legally recognize each other's copyrights. So he can sue the Chinese company in his country, and when they don't show up send Apple a notice to freeze assets related to the company, which just needs a US lawyer. In the end the lawyers win, but it is a straight forward case (assuming all the facts are as given...)
Yes, you likely could threaten Apple with a lawyer.
But based on your comment you likely have never dealt with a lawsuit, especially involving several jurisdictions. And trust me, the lawyer want the same thing as the scammer. Your money!
Maybe it is better to sue Apple instead, for allowing such apps - they claim they have "strict guidelines" and review all apps before accepting them .... If many developers around the world start doing this, it becomes a PR issue and costs them money too in legal fees ... may even force them to fix the issue.
