I'll try to look into it but I don't think that will help.
Here's what I found (actually, it's speculation). Both asserts are the result of a failure in the same fw routine. The routine seems to get a focus lens 'lock handle'. If the focus lens is locked (by another routine), the function immediately returns with failure -> this leads to the assert.
One of the asserts happened in capt_seq_task (this could be initiated by CHDK), the other one happened in a task named CZ (computerzoom). This seems to be the result of concurrent focusing attempts.
I'd try to disable everything which can alter the focus (thus my previous suggestions). I'd also try to increase CAM_NEED_SET_ZOOM_DELAY, perhaps 300 milliseconds are not always enough for completing the zooming process.