With a splash parent, all offspring will receive a copy of the blue gene. Henk's calculator makes assumptions about the specific genes involved, which may or may not hold true for a specific bird. With black, blue and splash, it assumes that the bird is E/E based. Depending on the breed, it may or may NOT be E/E. And if it only has one copy of E, that allele would give the base for THAT bird, but not for offspring that did not inherit E. Don't take me wrong. The calculator is FANTASTIC for predicting the results, but the more you know about details of the genetics of different varieties, the better you can understand the limitations.
With cochins, there is a good chance that the splash are e^b based, although they could also be E^R based. The buff could be e^b or E^Wh based.
Experience says that you will get some birds who are blue, some who are buff and some who display a mix of the two colours. Blues may leak some gold, depending on other factors.