We’ll just have to disagree.

You are rejecting my point simply because you don’t like the conclusion. You are determined to press your case fixating on the MEANING of a Replacement Proverb, which we cannot understand because it’s an ancient proverb fossilized and repeated until nobody knows what it means, but they know when to say it, like responding to a surprising revelation in English with, “How about that!”, which uses a combination of words that make no sense together whatsoever, but we all know “what it means” because we’ve witnessed so many people utter it under similar circumstances.

So, here’s your new assignment:

Explain what “How about that!” means in English, breaking down the grammar and explaining the choice of each word in relation to the meaning of the sentence.

When you can do that, I will be eagerly reading your insightful deconstruction of Klingon Replacement Proverbs.

I think you're missing his point. Whether or not the Klingon proverb is a fossilized expression, the fact is that we do have a translation of it as if it were a sentence constructed from modern grammar. reH latlh qabDaq qul tuj law' Hoch tuj puS is translated The fire is always hotter on someone else's face. Whatever the true meaning, structure, and origin of the Klingon, it was translatable. Whether that translation is an accurate interpretation of the Klingon is another question. But the point is that some meaning, somewhere, was taken out of it and translated into an English sentence.

You gave How about that! as an example of an untranslatable English expression. This is something different than the above. If we accept your claim of untranslatability as true (and I don't, because the Klingon expression toH! seems to get quite close), then it is inapplicable to this discussion of a translated superlative.

(I have read that how about that comes from the more general how about [blank]?, which is an alternative of what about that, which in turn comes from an archaic what say you about [blank]? So the grammar here is unmysterious. The how is asking your reaction: how do you react? The about that is specifying what you are supposed to react to. The expression is used rhetorically: I express my surprise as the answer to my own question. How about that may be a fixed expression with a fixed meaning, but that meaning is not completely lost in archaic grammar.)

I think you're both assuming too much. You're assuming the expression cannot be analyzed in the normal way. De'vID is assuming that the English translation accurately reflects the meaning of the Klingon proverb. I don't think either position is clearly supportable. The Klingon sentence is odd, the English translation is odd, and no Klingon has explained it further.