In real life, most wide bodies, including the A350 use L2 to board instead of L1. 

Im not part of the ini team but this has been discussed on FBW's discord and also on GSX's support forum, the problem is MSFS in itself, the jetways always choose the closest door to the jetways starting position, i don't think there is much inibuilds can do about it, hopefully they can chime in it that isn't the case.

In the meantime you could park the plane further forward so that the jetway is closer to L2 then it should connect to it instead of L1

 

PMDG figured out how to deal with this issue. Although MSFS has jetway limitations at the moment, aircraft devs can bypass this by tricking the sims interactive points to allow the sim to see the L2 door as the L1 door instead. The result is that no matter where you park, the jetway will always connect to that door. This is a very simplified explanation, but the devs should be able to implement this in an update.