If she is already able to teach and seems to be a partner in a private daycare or school there would be no need for her to return to school. Also no need for her to attend school in Canada. Yes there is no age limit when it comes to studying but it must make logical sense based on her career, her family and must make financial sense. Many try to return to school when they don’t qualify for other immigration programs with their families. You seem to have a very nice life wherever you live. It would make no sense for your wife to return to school in Canada to study what sounds like early childhood education. If she was looking to do a PhD then her chances would be a lot better.