A reservation won’t be automatically valid on a different train as it is a booking for an individual seat on an individual departure.

If a connection is missed due to a railway delay/issue then the best advice is to seek assistance from rail staff, it is the responsibility of the railways to help you in this situation, including with finding a later connection without any extra cost, or extra use of your pass in the case of travelling an additional day you hadn’t intended on validating your pass for.

How willing staff will be is always going to be variable, unfortunately. It is also reasonable for any language issues to be the passengers place to deal with if you don’t speak the local language. Phone apps/translation and writing translations of simple facts down is a good idea.

Being pro-active is also advised, if you are on a delayed train and don’t think you will make a connection the earlier you try to find assistance the better chance you will get a good resolution.

Thanks for the information 

Appreciate