TLDR: Allow plenty of time, at least 30 minutes, to change trains.
I’m coming to the end of a 5 week cross-Europe trip, it’s the first time I used the Eurail Pass. I booked all the seats and checked all the times of the trains through the Eurail website and I think that was a mistake.
Some of the journeys involved 2-3 changes, and the plan that was presented by the Eurail site at first seemed OK; a lot of changes were 10 minutes, and at the time I thought that would be fine, 10 minutes is plenty of time to get from one platform to another I thought, and we only have hand luggage.
Not so - quite a few of the trains arrived late, which involved a dash to the board to check the departing platform (although some trains display these as you arrive), then running up and down stairs and along corridors to the next platform. My wife fell at one and bruised her knee, and one train we got to as the doors were closing.
The algorithm used by Eurail doesn’t seem to take into account trains may be delayed.
The sitcky in this forum advises using the train company websites, and that is the best advice, and I would add to allow at least 30-45 minutes to change trains.