In order to see your tickets, you must have bought them as an authenticated user. It won’t match your tickets just because you bought them with the same e-mail address yet without having been authenticated. If it would, this would be an IT security breach.
Regarding seat reservation:
As a general saying, in Switzerland, train tickets do not have a seat assignment as tickets (except of type Supersaver) entitle you to use any train connection regardless the time of the day or connection chosen during online ticket purchase.
There is actually no need to reserve seats for your trip as there will be enough seats available on the train. Swiss people never reserve seats, except for the panoramic trains. Because the Swiss rail system is considered mass transit just as metro lines else where: you get to the station, you look up the departure board, you choose your destination, you get on the platform of the next train service, and you hop on the train which leaves every 15, 30, or 60 minutes. On board, you choose an empty seat and you enjoy the ride - so easy.
If you want to make a seat reservation, though, simply use the link that you mentioned in your question. Select the required train connection - done. The seat reservation system does not care about the existence of a valid ticket for the selected train; latter is the sole interest of the ticket inspector (so am I) on board the train.
Get back if you need more help. Wishing you good travels.