Yes I have read that Pali could have been a trade language.
Interestingly this method of textual comparison has also proven useful in tracing the history of the “Hindu” Samkhya school; one of whose early works, lost in Sanskrit, is preserved in the Chinese (Mahayana) Buddhist canon.
I’m interested in the Sankhyans! Any reference?
Sorry for the late reply but as an introduction I suggest “Encyclopedia of Indian Philosopies Volume IV: Samkhya A Dualistic Tradition in Indian Philosophy” Gerald James Larson & Ramshankar Bhattacharya (editors), Delhi, Motilal Banarsidass, 1987.
There is no question that there are some later additions. There are even some contradictions. But by comparing different passages and comparing with the Chinese Agamas, we can get a pretty good idea of what the Buddha actually thought.