I suspect that the problem with all of these attempts is that you are all trying to expand upon an idiom that is essentially not grammatical. While you can explain the obvious Sentence As Subject as a not-slippery-slope idiom that can’t be generalized, you then proceed to use it with a conditional that isn’t part of the original idiom, which is essentially an attempt to generalize it to make it more useful than the restrictions of the original idiom.

No. The problem with this isn't the apparent sentence as subject. The problem with it is that the conditional applies to the hypothetical pu' DIlo', but in the proposed solution pu' DIlo' is stated as fact. And if you try to make pu' DIlo' conditional, you're trying to use a conditional as the first sentence of a sentence as object, something we don't think is correct. The fact that the 'e' qa' construction seems to employ a sentence as subject is completely irrelevant to the issue we're seeing.

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SuStel
http://trimboli.name