We're talking chalk and cheese here, I feel. CZ lenses are so much "better " than Yashica lenses, and that's that. However, I am not complaining about Yashica Lenses, especially the ML series. Camera Magazine ( Uk early-mid 80's ) tested a range of focal lenses from ALL the Camara makers, 24, 28, 35, 50, 85, 135, 200 + 1 macro, ( all Manual focus ). Yashica came out 3rd in most of the focal lengths, even beating Leica in one case, ( 55mm Macro, if I remember correctly), better than Olympus, Canon, Nikon, Minolta, and much better than the Independant makers'.
I bought a Y 28mm F2.8ML, years ago as I didn't have a great use for the length, but decided I couldn't be without it " just in case" I bought it because I couldn't justify the expense of a CZ. I used it many times and cannot complain about anything, except perhaps flare control. For £ 50 new, it was a cracking lens.
Horses for courses, I'm afraid. If you want CZ quality, buy CZ. If you can't afford, or cannot justify the price, then don't expect CZ Quality.