In many cases there are better places to get reservations, yes.

This thread describes many alternative reservation sources.

If you want more specific advice then say where and when you are planning to travel.

In most countries you can also travel without reservation. Check the "no sest reservation" filter in the Railplanner app or look for reservation free trains in the timetables of the national railways. 

In which countries are you planning to travel?

Allora le tratte con la prenotazione sono Berlino-Varsavia, Varsavia-Cracovia, Cracovia-Praga e il treno notturno Budapest-Bucarest. Ho visto che provando a sostituire con tratte senza prenotazioni, esce veramente troppo lungo. Consigli?

Berlin-Warsaw: ticket office that sells international reservations (from 60 days in advance). Doesn't need to be in Germany. Alternatively, call DB (there's also a number for Italian) and then pick up your reservation from a DB ticket machine when you get to Germany.

Warsaw-Krakow: on intercity.pl (30 days in advance)

Krakow-Prague: cd.cz (60 days in advance), check the "Reservation only” checkbox after 

Night train Budapest-Bucharest: there are 3 night trains on that route. Only the last one, leaving Budapest at 22:45, can be booked online on tickets.oebb.at: add the Interrail/Eurail discount for each passenger and then select "One-way tickets” (NOT "Seat reservation only”). The other 2 night trains cannot be booked online. Book them like Berlin-Warsaw above.