RolandP
The official rule regarding Supersavers according to the SBB website says “Where a train is cancelled or delayed or a route is closed, you may use the next connection with confirmation from the ticket inspector or sales agent.”
… so strictly according to that, the “next connection” which is the IR90 (1715) leaving Vevey at 10:36 should be taken.
Now as you are suggesting the earlier connection: Does that mean that in real life, ticket inspectors are more “flexible” than what the rules say?