Most agents haven't a clue about seat pitch and as noted cannot access this on their own systems. This is clear every time I mention I don't want a seat in the forward "preferred" seating in Economy on narrow bodies...for the reasons we all know.
As for AC's widebodies, why do you even have to ask the question? There is virtually no difference among seats in any economy cabin on any aircraft in the widebody fleet. AC has a better pitch than LH and most other European carriers in their longhaul back cabins. It really makes no difference if you get a seat in the "preferred" forward economy cabin or the rear one.
Why even bother with this question?!