Will the sister be committing a sin if she sponsors her brother to come to Canada, while he is not committed to the teachings of Islam to the required extent?

It is permissible to reside in lands of disbelief under certain conditions: the ability to openly practice one's religion, to perform its rituals, and to be secure from temptation (fitna). If you fear for your brother that he might succumb to temptation due to his weak adherence to his faith, then it is not permissible for you to help him come, based on the Almighty's saying: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression). However, if you hope for his rectification, or if you are able to take care of him, and there is a benefit in his presence, then there is no blame upon you in sponsoring him.