It is very interesting that Lal was nor able to find any reference to the 5 niyamas in the tripitaka. In my understanding dhamma niyama, utu niyama, citta niyama, bija niyama are probably some of those conditions that would decide whether a kamma has a chance to come to fruition. Refering back to lals example of angulimala who killed thousands before attaining arahathhood it was his mindset of being a arahath that stoped all the kamma vipaka. What I am trying to say is if a tree bears fruits one can say it is because of the soil, another can say it is because of water. But in reality all conditions water, soil, sunlight etc has to be there together with a seed to create the tree that bore fruits. But if the seed wasn’t there no amount of sun or water or soil can create a tree. So may be there is a kamma beeja (seed) behind everything that happens. Its just that kamma can not come to fruition by itself without favourable conditions. Anyway its just my way of thinking.