Two things:I think that Calumetville is located in Fond du Lac County, so I did another search there.I did locate other Roberts that appear to be from NY, but there was no William and Joanna, per se.
What I did find is the following:
1850 Census, Wisconsin, Fond du Lac, Calumet
Robert, William 28 Germany Jerusha 25 Germany
Although this William claims to be from Germany, his age does fit.And Jerusha...well, it's possible that this is either her 'real' name or the census taker got it wrong.Then again, this may just be another couple all together!