'has yet known' is correct and usable in written English.
You can use it to express that something has not been discovered or experienced yet. For example, "The secret of eternal life has yet known."
It is the greatest body of poetry the world has yet known.
On the other, it offered the most abject lesson the world has yet known in the genocidal atrocities that bigotry can unleash.
William T. Tilden 2d, the greatest tennis player the world has yet known, recently offered to wager that within two years young Baron von Cramm of Germany would be a new world champion.
Incredibly talented people animators, artists, actors, composers, directors bring video-game stories to life, and games themselves might represent the most collaboratively complicated entertainment medium that the world has yet known.
Incredibly talented people — animators, artists, actors, composers, directors — bring video-game stories to life, and games themselves might represent the most collaboratively complicated entertainment medium that the world has yet known.
Jealousy gave him "a most intense suffering he has yet known" and Swann's sufferings are real, they are recognisable, they are at the heart of all love and at the heart of this book.
He was 35, serving in his first Syrian government, the most extreme the country had yet known.
Michael cultivated a misanthropic air, but drew people to him more compulsively than anyone I've yet known.
The effect of blocking Sox2 activity on germ layer formation has yet not known in Xenopus embryos.
These post-translational modifications could help to mediate the fine tuning of SbMYB44 activity, although no function has yet been known for these post-translational modifications.
The coach probably already knows (most people run background checks before hiring someone), but your team has yet to know.
