This is kind of ridiculous. The purpose of reserves is not to send political messages. It's to provide a mechanism to manage monetary policy and it does that through buying back its liabilities.

To do this effectively you must hold a strong currency as your reserve- there's no point holding Zimbabwe dollars. So any reasonable reserves for a European country today will be part Dollar, Pound, Yen and Yuan. How much of each should be proportional to how stable that currency is and how highly correlated it is to your own currency.

This is not a political message, the ECB is just neutrally moving more towards Yuan as the Chinese economy gains importance relative to the US economy. That's all. It's not a good sign for the US, but the ECB has better ways to send political messages than buying $X00m dollars or Yuan.