For what date?

looking at feb 2023

"February 2023” is rather vague.

That being said, the rail planner app and website are not very reliable. The DB website shows trains, e.g. on February 1st:

They can be booked 60 days in advance.

You have it exactly - I know the train exists from the dbahn site (plan on taking the 9:51) but it does not appear in the eurail app.  

As tickets are not yet on sale i will wait to make my reservation and maybe the app will have been updated by then?

The beauty of the pass is that one can be vague of course ;-)

Probably. What's in the app right now, is not so important. It only serves to register your journeys; by the time you travel, it will usually have been updated. It's the Interrail website where you can book reservations, but Interrail have a 2€ booking fee per person and train and only send reservations for this train via post, which will cost an additional 9€ per order. It's better to book this reservation at a ticket office (can be done in many countries but not in the UK) or book by phone via DB and then collect it from a DB ticket machine when you get to Germany. Price is 4€.

INside PL it will on open 1 month before-give or take.

There is currently also a reported ´Sperre=blockage of all RES even before the timetable change date.

It should be blind obvious that RES can only also be made when normal sales are allowed-as on this train all seats are RES

Sorry what is PL?

INside PL it will on open 1 month before-give or take.

TIA

mcadv has a very short, unclear way of writing full of abbreviations.  You’re not the only one that gets lost in his “texts”.

I guess in this context, PL means Poland.