William seems to be my ancestor as well. I located the baptism record you have attached. Interesting fact: Cornelius Connell is listed as a "witness" or "Godparent" at Margaretta's baptism. William and Jane's second child is Cornelius Powers (my Gx3 grandfather). My assumption is William and Jane had great admiration for Cornelius Connell, enough to make him their first-born son's namesake. I consider this a small bit of confirmation William and Jane are the right ancestors for me. I have the actual handwritten church record from which your document was transcribed. I also have the St. Mary's 1827 Church record of the marriage of Power and Connell.
I'm hoping to find the exact Ireland town where thee two lived. I have a good amount of info on the family AFTER they emmigrated to Canada. I've confirmed the family facts AFTER they arrive in Canada, but have precious little confirmation or doucments from Ireland.
In addition to the Ireland town in which the Power couple lived, I am curious what happened to William in Canada that he died so young.