I’ve experienced so many serious shortcomings with EurailInterrailRailPlanner, that I consider it an unreliable source. Routing that puts me on a bus instead of keeping me on the through train to the destination, a complete ignorance of Italian train scheduling for connections, missteps when routing to avoid seat reservations, total failure to place a selected seat reservation in the cart for purchase, telling me there are no trains to a destination when the German S7 lines accept a EurailPass, etc.
At best, use it in conjunction with Google Maps, get reliable schedules from the train companies directly, search on your own leg by leg to plan connections and transfers, show EurailInterrailRailPlanner results to station ticket agents to get a good laugh, learn precise names for destinations for typing them in because EurailInterrailRailPlanner is not smart, buy your seat reservations on high speed trains through a station agent well ahead of time. I don’t hate EurailInterrailRailPlanner, I’ve channeled my disgust into constructive workarounds, but Eurail should be ashamed of itself for putting out such a shoddy product. It isn’t free if it leads you into making mistakes and missing opportunities.