It shouldn't need a 16# recoil spring to cycle properly sized cartridges like you've tried. 14# is stock for the 9mm B.
You insinuated the ejected cases were being thrown a looooong ways---true? If so, possibly the spring isn't the correct weight or has a defect. I've not heard of this happening before now.
If you don't have another recoil spring handy you can do a kind of 'hokey' but simple test. This is a "dry fire" test: Shim the front end of your recoil spring about 1/4" or so. Cut off 1/4" of a dowel with a diameter slightly larger than your spring diameter and insert it into the front end where the spring rides---it needs to be a loose fit

. You could also use washers or a 'whittled down' piece of wood. This will increase the spring weight to check for proper feed using your snap-caps. If the pistol feeds, I'm not sure this tells you 'why' it isn't feeding. It sure sounds like something hanging up or a 'bad' recoil spring.
You could call CZ and they might send you a new "stock" recoil spring based on what you find out with this test.
Good luck.