It seems YUL-FCO goes year-round
As per the last updating through GDS Air Canada appears to extend YUL-FCO service, which was supposed to be seasonal ending Sep30, to all year-round.
New schedule shows that in october AC will be flying 5xw FCO-YYZ + 2xw FCO-YUL-YYZ with A-330, then in the IATA W09/10 3xw FCO-YUL-YYZ with 763.
In addition, on a side note, between Jul 16 and Jul 31 the 77W will be routed from YYZ to FCO every Th/Fr/Sa iso 763.