Theoretically, the country where the bank account is located will tax it. So in her case, if it's a bank in LATAM, she will have to pay the tax once fiat lands in her bank account.
Now, this is all practical theory, you should check with a tax specialist as well. But i believe this is the case in this matter
IMO you are right, but what if the crypto assets have also generated some profits while under his name in the European exchange account? would Europe not want to task the profits you got while it was sitting in his own wallet. These things are very technical and complicated and as others suggested, I would advise he seeks the opinion of an expert before proceeding so that he is not eventually double taxed.