Civil birth and death records were not well kept in those eras in Wisconsin. Church records - baptisms and burials - may become your primary source. If you haven't already figured out what those might be, post some requests for the most logical Catholic or Protestant churches in the area where they lived (from the census records?). A church burial register can be more reliable than a cemetery record. The Mormons microfilmed the extant Catholic church registers, and many of the Protestant churches.
There may be Waukesha County probate records for Bernard, even probate notices published in the local papers.