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I never tried the Yashica lens, but my experience with older lens designs outside of Contax/Zeiss and Leica is, that because of the requirements of sensors, the "cheaper" WA are not dsigned for these requirements. For telezooms and normal FFL this is not that big issue. But the wider it gets, the more difficult it is. Googel for all the complaints of Sony Nex7 users, which treid their exoensive Leica and Contax WA lenses on it....
Olympus published years ago a long artile about this telecentric design requirement. Although they exaggerated a little bit to push their own new FT system, it still holds true. This is why all manufacturers sooner or later brought newly designed lenses on the maket. The more demanding a sensor is (in MP), the more problems will come with old lenses.
The Contax lenses, especially the 21mm, is famous for its design compatibility with modern sensors (below 24MP). But the Zeiss 21mm is so expensive, that it is easier/sheaper to buy a new design from another manufacturer and buy & use it on another DSLR. This will be still less expensive