I… erm… I don’t know if you are doing this deliberately.
An 8% rise where half prices half is not beneficial for affordability - I showed that already. You then showed a 5% rise where the house prices halve is beneficial. But the problem with your workings is that it’s an unrealistic scenario - you basically fiddled the inputs.
Clearly, the affect on affordability will depend on what the interest rate rise is and what the house price drop is. I don’t understand why you don’t understand that showing that one particular instance of a relationship is not the same as demonstrating that the relationship itself holds true.
All I can say is that you are basing everything on a huge misunderstanding of basic math.