Can a canted fsb be the caused by taper pins put in from the wrong side?

I have zero experience with that type of situation but, I would tend to think that might be a possibility.

Taper pins can be installed from either side, if they were machined from that side.  So the answer to your question is no.  There does seem to be a standard to drill them from the right side, so they come out to the right, like the receiver take down pins, but there is no specific reason for them to be that way.  At least one company is known for installing them from the other side.

If someone removed taper pins and tried installing them from the wrong side, they wouldn't get very far because the pins are tapered, and the holes on the "wrong side" are too small to allow the pins to go in more than a fraction of an inch.

If you have a canted FSB, someone simply installed and pinned it at the wrong angle, or it was done properly, but the whole barrel assembly may be cocked in the upper receiver.  That can happen if the slot in the receiver, that accepts the barrel alignment pin, is too large, or if the alignment pin is snapped or loose, and it allowed the barrel to shift to one side when the barrel nut was torqued.

If the front sight is canted the taper pin holes were not drilled perfectly. It doesn't take much to be off center.

Since we have adjustable sights it can be worked around unless grossly out-of-spec.

Armalite sells a clamp on windage adjustable "National Match" front sight base that easily replaces the standard sight tower and can be adjusted so the rear sight is centered in it's range of adjustment. It will not withstand actual bayonet use if that is something important to you.

Very few rifles come from straight the factory that zero with the rear sight centered in it's range of movement.