Thank you for your research into that question.
I see your argument.
Could it also be that Ven. Ledi Sayadaw teached the Dhamma according to his understanding to the Westerners?
In that book, there is a letter correspondence with Mrs. Davids, I believe that is the wife or Mr. Rhys Davids. She asked Ven. Sayadaw a question about niyama.
Could that be possible?
According to my knowledge, the Tipitaka was found in Sri Lanka. It must have been present in Myanmar, too, right?