u'enderfu fu'ivla

x1 (event) is impressive, awesome/awe-inspiring, wicked, really good, wonderful (either sense), acceptable (downplaying the intensity of the word) to x2 by standard x3.

This is not merely good or acceptable. It must be impressive and may not even be directly beneficial to the observer. Watching a chess master tearing through one's defenses is bad from the standpoint of the game (since one is losing horribly), but it is still a privilege to watch because it is so awe-inspiring. For the sense of "cool" which means "stylish", use tre'endi.

In notes:

x1 is cool/trendy/fashionable/in style/hip/chic/sophisticated-and-socially-desirable to x2 (observer) by standard x3.