Most accurate is the local railplanner of the operating train company not all Railcomapnies share frequent their timetable with Eurail :)

Great, thank you for the reply! I found RailEurope and am using that to check that the times I am reserving seats on Eurail match up with that website’s times. It’s the app that seems to be the most outdated.

On that note, do you know if manual entries are reliable when adding trips to my Eurail pass? I have a mobile pass, and need to add trips on the days I am traveling to my pass, but what would I do when I can’t find the same listed times/trains on the app as on the website? I put them in manually, but am skeptical that will work.

Yeah just add them manually :)