The wording definitely intrigued me, and I understood the implied "given current models". I think sparking curiosity is more important than catering to someone who is not the target audience of a university news article.

That's a lot of damage for two words!

Can you suggest an equally terse title that would avoid problems such as "position[ing] scientific theories as normative rather than descriptive" and "mak[ing] refinement look like failure"?

I think you're assigning far too much wrongdoing to this perceived sleight here, I wouldn't even think that saying "our current understanding makes this look impossible" is a way of saying we shouldn't celebrate change and improved understanding, I would instead go the opposite way and think how interesting it is to find things outside our understanding

I'm sympathetic to your point, but this usage of should in a non-normative way is also thoroughly colloquial and understood by pretty much any native english. Maybe there is some slight, subconscious coloration, but I can't think of other things which have had a bigger effect on the public's distrust of science than leaving off "according to our best model" from the end of a sentence.

Refining theories was banned in 2020 /s.