Firstly let me say thank you for taking the time to read my post and look to the reference material. There is quite a lot in your post, so I will deal with the question that has the largest impact first - the decapitation scene.
To explain why this scene is important, my theory posits that the stories of the Westcar Papyrus are inherited from a tradition of orality and were written down in their middle Egyptian hieratic much later than their creation.
Where orality prevails as the means of information transmission, then information is encoded into mythology. Making a myth more memorable requires vivid characters and emotional scenes typically trauma. The decapitation scene sets this up in multiple ways. Of course forewarning of decapitation is horrible enough in the story but decapitation is the worst means for a person to die in ancient Egypt and was typically reserved for the very worst enemies of the state. In Egyptian religion, it was believed a death by decapitation robbed that person of any chance of afterlife. Therefore I see the decapitation not only as a significant trauma but a signalling of important information being encoded.
With the constellation Taurus the bull likely encoded as one of the victims and the lion being tamed being associated to Leo, we can investigate the zodiacal constellations between these two. They are Cancer and Gemini. Given the story seems to lead us to a moon setting in Gemini, I propose this is an element of repetition/recursion in the story to focus is on the right area of the sky.
The identification of the two geese is something I’ve been unable to achieve. I don’t think it’s the man in your link but that was interesting.