AC issued my ticket but the outbound flight (BOS-MAD) is on LH metal via FRA, while the inbound flight (MAD-BOS) is via YYZ with AC. This change affects the inbound flight. I am prepared to be yelled at, but can I also ask to see if changes can be made to my outbound flight as part of the request (rerouting or a different connection, etc.)?

The rule says the following:
In the event of a scheduled irregularity, carrier will either:
a) Carry the passenger on another of its passenger aircraft or class of service on which space is available without additional charge regardless of the class of service; or, at carrier's option;
b) Endorse to another air carrier with which Air Canada has an agreement for such transportation, the unused portion of the ticket for purposes of rerouting; or at carrier's option;
c) Reroute the passenger to the destination named on the ticket or applicable portion thereof by its own or other transportation services;