I know you want to help but I kinda know how things works 
I tried with many different ways and it does work for other users and this is not the issue here.
The issue is that the OS does not forward the command to Yatse but to other apps, the command is perfectly received by the OS.
The Watch logs are the exact same the media button is not sent to Yatse. (And no there’s no plan for Tizen)
As I said if it’s due to some Yatse change the only way to progress is that you find out the last version of Yatse that works since you said it worked before. If no version works anymore then it’s not a Yatse change but something else that is yet to be found.