I feel your pain, we did a similar thing over the summer, not changing print servers but getting in a fleet of Kyocera copiers and printers. I've had no problem, yet, with the copier KX drivers but had loads of problems with the KX drivers for the 5350s we have. But I did eventually find one that seems to work.
Try downloading the KX driver at the top of the list on the Kyocera website, it's the Microsoft signed one and extract it. When you come to pick a driver to install choose the 5030 KX driver. I had loads of issues with the 5350 driver!! But the 5030 seems to have cured most of our issues. Never use the drivers on the CD, they are useless!