tl;dr: EU regulation 1371/2007 describes in articles 16 to 18 train passengers' rights to reimbursment, re-routing, compensation and assistance in case of train delays and cancellations. Are these rules, and if yes, to what extent, applicable to passengers travelling on Interrail or Eurail passes?
The regulation only mentions 'travel pass or season ticket' holders in the context of monetary compensation for delays and for each delay more than 60 minutes, Interrail and Eurail pass holder can indeed request a refund of a part of what they paid for their pass.
Since the rules for re-routing and assitance do not mention ''travel pass or season ticket' specifically, my first assumption would be that Interrail/Eurail pass holders are entitled to the same support as regular ticket holders, but the railway companies seem to disagree.
Let us assume the following situation: A family is travelling with Interrail passes from A (in Germany) to B (in Italy) with several changes of trains and are planning to reach B during the same day and have therefore already boooked a hotel there for the coming night. The first train has a significant delay causing the first transfer to be missed and the family realizes already now, that they will not be able to reach B the same day. During the first transfer, they ask at a DB ticket office if they can get help to arrange accomodation in C (they now assume to reach C before night) and are refused any help from DB as the DB employee claims that the family has to arrange new accomodation themselves and are not entitled to any assistance from DB.
This leads me to the two following questions:
Article 18 of the regulation requires that passengers in case of a delay shall be offered 'hotel or other accommodation, and transport between the railway station and place of accommodation, in cases where a stay of one or more nights becomes necessary'. Is there any obvious reason why Interrail/Eurail pass holders are not entitled to such assistance or was the family in this case misinformed by the DB representative?
Article 16 gives the passengers a right to re-routing if a delay causes a connection to be missed and to continue the trip on any other reasonable trains to reach the intended destination. This may seem irrelevant for pass holders, but Interrail/Eurail passes are not necessarily sold for a period, but can also be sold for a specific number of 'travel days'. If in this case, the family intended to use one 'travel day' to get fram A to B, but had to spend the night in C because of delays, should they in this case not be allowed to continue from C to B without using an additional 'travel day', even if they are (unintentionally) required to continue the following day?
In this particular case, the family eventually received compensation from their travel insurance for their additional expenses, but is there anything elsewhere in the regulation or precedent rulings allowing the train operatiors to bail out in this situation and refuse assistance?