Most rail planners use live data and will usually give good up to date information,

The IR planner does not follow live info as it is intended to support travellers without access to the Internet. Instead it updates its database frequently but not necessarily daily.

However all these rely on the operators sending the data to the core database these planners use.

Trainline is one of many real-time planners you can use, but the definitive source will always be the operators own site. OBB and D Bahn are probably the best for a wide range of European trains.

Certainly for future planning Trainline is one tool you can use.

Remember if you want to board a train but can’t find it in the IR planner you can always add them manually to your trip and then to your pass.

Both bahn and oebb (scotty) cover nearly as much as this trainline and even give more options/warnings about some areas.

Bahn and Oebb are journey planners, trainline is a booking engine. There is a difference, the planners will generally show all options, a booking engine is focused on selling tickets so may well be set to suppress anything it cannot generate a ticket for.

Many thanks for all your great answers. Very useful !