ok... He can not calculate a percent chance for CropBreeding that is impossible, unless he can see the Future... xD
If you mean that Ferru has a 0% chance of appearing when breeding Stickreed x Stickreed, you could be right, but if you mean that the chance can't be calculated, I have to disagree: all the plugin would have to do is calculate the weights for each possible result, then add them up and divide each weight by the total to get a percentage chance. I wrote myself a small program to do that back around November or December of 2014, but I deleted it.
What I've been doing lately is breeding my existing crops to get more of them, and if I happen to get something different (other than a weed), I let it grow, and then try to transplant it into a separate field for that crop type.