I'm fairly new to booking rewards and in the process of transferring all my AC miles to US to book a Star Alliance ticket due to their lower requirements for points redemption, I live in YYZ. To book a reward on Star Alliance through US does it need to originate in the USA or can it be in Canada?

I'm looking to book YYZ->ORD->NRT>TPE (with stopover in NRT) and return from TPE>PEK>YYZ (no stopovers).

Can I do this or will I have issues?