Zetor has the flexibility, technical knowledge and financial reserves to develope a CVT (like they were on the cutting edge of technology with the Crystal range in 1968 ) but most tractors up to 200 hp are still sold with a standard 4 step powershift transmission, because these are more efficient.
Anyways, if there was a technology that was cheaper, yet more efficient than the current transmissions, i bet they would be interested.
Also the current range of Zetor engines with a torque backup of 35-40% have enough lugging ability to outperform many CVT tractors. CVT's adapt speed to power, an engine with high torque backup adapts power to working speed.
To say it shortly, Zetor can develop many things but there is no need for fancy stuff, farmers need rugged stuff with high work output. CVT doesnt allways improve working efficiency....
Also, the most popular tractor class among farmers is still the purely mechanical, 70-100 hp utility tractor, and for part time farmers/hobby farmers the 30-50 hp compact class. That's where Zetor development pinpoints now, with the Proxima Plus models of 80-100 hp, and the Ploxima Elite 3 cylinder compact and orchard range which is to be introduced within a year or so.