Indeed it can be confusing.
OBB is definitely a valid option. Rail Europe (desktop version) works for me: its main benefit is that seat selection is available.
Ok, thanks. It was the inconsistency that threw me more than anything - different update schedules and/or sources explains it.
By the way - the "theory" that raileurope still works for reservations seems not to be true (or maybe it is just me) I've been making reservations using OBB because it works..
The summer timetables for some Italian regional trains have just been published and it's possible that there are some discrepancies in the data.
Rail Planner is updated every other week (and works in offline mode) and eurail.com twice a week I think. In a week or two the times should match.
For actual planning it's always better to double check with the railway company and DB Navigator/bahn.com (connected to the European database and updated almost instantly).
About your route: there are frequent reservation-free regional trains and slightly faster IC trains (3€ required reservation, available through Rail Europe to avoid fees).
https://www.seat61.com/interrail-and-eurail-reservations.htm