Thanks for the context; how do you think this impacts plausibility? Presumably the fact that he made progress in a well studied passage is cause for skepticism? What's your take?
To illustrate how things can go wrong, let's try to prove that English is a Semitic language. Suppose that the source material we have is this sentence:
"A baker brought a bushel of wheat to the mill."
Now let's match it to Semitic roots as found on this list: https://en.wiktionary.org/wiki/Appendix:Proto-Semitic_stems. Let's look for plausible substitutions now:
- "Baker" matches "bVkVr-", "first-born son". We have our anchor now. (V means any vowel).
- "Brought" looks plausibly close to "burāṯ-", "juniper" on our list. So far so good.
- "Bushel" is a good match with "b-š-l", "to be cooked"!
- "Wheat" does not have an exact match. It could be a loanword, for example.
- "Mill" looks like "m-r-r", "bitterness" if we assume lack of written L/R distinction. Again, juniper + cook + bitter is plausible, because juniper can be bitter.
- The meaning of particles will be inferred from the sentence structure.
Okay, let's take a look at our translation! We have "first-born son", "juniper", "cook", (wheat), "bitter". Pretty clear that (wheat) must be the name of a dish here. Therefore, the sentence can be translated as "A bitter juniper dish is being cooked for a first-born son". This even matches the context: the sentence was found in a granary, and it refers to food.
My point here is that with such a small sample size, we can extrapolate the data to mean absolutely anything. With no reference material, we cannot assess the correctness of any translation.