Of course, the moment you have called the SEN hotline, you can also just change your seat assignment right with them and save yourself the extra hassle.

Generally, my experience is that as a SEN, bookings on swiss.com auto-assign my seat type of preference (aisle / window) and generally in the front third of the cabin, although not necessarily in the first few rows. On the Avros, I got the seats under the wing with limited overhead space all the time.

As a rule of thumb, I usually call for flights >2h to get the seat I really want. Below that, I don't care much and deal with it during OLCI.