Did Agnes also go by the given name Augusta? In the 1920 Census she's enmuerated as "Agusta." William's WW1 draft registration states his next of kin is Augusta (wife), and they reside at Tow Path (same street as on the census records), East Syracuse, Onodaga Co, NY. Incidentally, although the 1920 and 1930 census records for William and Agnes give different town names, the street name is the same on each (East Syracuse village is/was an incorporated place of Dewitt Township in the 1930).
While William certainly could've certainly arrived in Canada and crossed the US border, he also could've sailed into Boston, Philadelphia, Baltimore, or any of the other US ports. Keep in mind, though, when looking for passenger arrival records, the name on the manifest would be the one appearing on his travel papers or passport presented to the shipping clerk prior to boarding the ship at the port of departure. So, you may not be finding it if you're looking for "William Wychules." William is an American/English given name, and Wychules is likely an Americanized spelling. :)