This does not seem likely.
There has to exist a reason for Wang Yi opening some cards, but Kaja Kallas is not that reason. Wang Yi does not make uncoordinated statements and Kaja Kallas isn't attempting to achieve that either.
Somewhere in the CCP political bureau, it was agreed that Wang Yi will send this public signal.
The reason could be something in China, something in Russia, something in Europe or in the US. What is the reason? I don't know currently, but I'm not the only one solving this puzzle.
Going by this article...
https://nltimes.nl/2025/06/30/brothers-still-deny-involvement-18-year-old-sisters-honor-killing
...I would speculate that by sending the letter, Khaled al-Najjar attempts to free his sons of complicity in the crime. Whether they are or aren't complicit, is for the court to determine. Getting the man back from Syria would be a priority for the court, but given the situation in Syria, this might be difficult to arrange.
The court seems to consider the brothers either plausibly complicit or a flight risk and decided not to free them on bail.
...and...