Because it is difficult to estimate when your plane will land, it is also impossible to predict which train you will travel on.
If you insist on reserving a seat, I recommend you choose a connection that departs several hours after the scheduled landing.
Reserving a seat after your landing in Switzerland no longer makes sense.
In principle, you can expect to find 3 free seats even without a reservation, but we cannot guarantee this.
Hope I could help you with this information.
Have an awesome weekend.
Kind regards, RahelW