It is important to realize that the issue here is only bodily suffering (or pleasure). Abhidhamma DOES NOT say mental suffering (or pleasure) is due to past kamma vipaka.
In Abhidhamma, all sense inputs via the other five sense inputs (other than physical body) are initially felt as upekkha (neutral) vedana. Only the bodily sense inputs could lead to dukha vedana (getting injured, headaches, cancer, etc) or sukha vedana (good massage, lying on a comfortable bed, etc).
When we generate joy upon seeing something that we like, for example, it comes in as a neutral vedana. We generate joy via “samphassa ja vedana” based on our gathi. A good example is seeing a well-known politician. Some people generate good feelings and others may generate bad feelings; but it is the same person they were all looking at. One may need to contemplate on this and let the idea sink in. It is an important point. It holds true for any sense input other than the bodily sense inputs.
I don’t think anyone stated otherwise above, but I just wanted to make it clear.
I still need to give this some more thought when I get get back. But one question from Siebe can be answered.
Siebe said, “. When one, for example, decides to stand on one leg for a day, one will surely feel very painful feelings.”
That is definitely a kamma vipaka. It is NOT a vipaka of a kamma done in the past, but is due to a vipaka of a kamma done AT THAT TIME. One would not feel such pain, unless one DECIDED to stand on one leg. That decision by oneself and the follow-up action led to the dukha vedana.
If one decides shoot oneself, that is the same. One DECIDED to do that. Kamma is action done with intention. Some kammas bring immediate vipaka, as in those two cases.
Another type of bodily kamma vipaka that can be DIRECTLY and EXCLUSIVELY attributed to PAST kamma arise due to anantariya kamma, like killing a parent, injuring a Buddha, etc. Vipaka due to anantariya kamma WILL be realized without exception. Those will be bodily pain (dukha vedana).
Some Brahmins of the time of the Buddha used to attribute all vedana to kamma vipaka. That is what the Buddha denied.
So, we have narrowed down the scope of what was said in those suttas (and Milindapanha) that Siebe referred to. We still need to address those specific situations related to bodily sensations.