Hello Uwe,
I have been doing some research trying to see if Apple had released any information about a bluetooth stack fix for wiimote. What I cam across was Remote Buddy. The developer claims to have to fix for the bluetooth stack. The application has a 30 day free trial. I personally do not have a setup to try it with as I have not yet invested since you do not have a work around. I dug a little deeper and the developer Felix mentions that he works with competitors to help them with their own work arounds for the issue.
I do not know if that will help you with your code but may be worth investigating.
I wish you luck,
MacinTurner