I just checked aircanada.com, and I see both flights showing with row 19 as an exit row

Row 19 is an exit row on all the XM 763s.

There are two layouts that would show up on aircanada.com prior to specific aircraft assignment (approx 2 days out):

1) The "regular" 763 with no mid-cabin lavs, with row 18 and 19 as exit rows, and 2) the 763 aircraft with the crew bunks, that have no rows 15-17, and row 18 as a bulkhead.

The third layout - with no row 17 and mid-cabin lavs, that has row 18 as a bulkhead - only would appear once the flight opens for check-in and a specific aircraft is assigned.

Sufficiently confused yet?