If it helps I understand the second much better and feels less clickbaity and includes more info. I do agree with the points you made about the confusion although I find frontier a term used in this area a lot, “frontier AI models have” would probably resolve that.
Imo frontier is too niche and specific, if you know what a frontier model means then it's fine, but if you don't then it's negative/detrimental to the title.
"new" does the same thing and is probably just a better descriptor then frontier
If the title simply said "AI is out-performing humans at CTF" then none of this confusion exists. Nothing is "broken," we don't need to be superfluous with "frontier," and the point is still there.