The Eurail website get less frequent updates and struggle sometimes as not all Railoperators have a open connection for foreign apps You can be sure that the train is operating when Trenitalia list them in their timetable :)

The problem is there are in Europe 2 european timetable changes one in December and one in June Some countries like Italy or for examlpe Poland have inbetween smaller domestic timetable changes and publish their data very late I guess that Eurail App team haven´t enough time yet to load the new timetable in their app :)

I recommend to use atleast one app besides the Eurailapp (My favourite are Scotty of Austrian rail or DB Navigator of German Rail as these cover most european countries but carefull these show even trains that are not covered by Eurail/Interrail and you have to validate them then via Eurail app )

I just tried both of those apps you recommended, and both of them do not show high speed trains after September 19th :/

This is driving me crazy

That just means that Trenitalia hasn't sent their timetable data for that period yet. You can try www.trenitalia.com; that site will have any new Italian data first.

I would have figured that the data would be available thru Eurail once it was published on the Trenitalia site, but if thats not the case, then that would make sense

That depends on how often Trenitalia sends timetable updates to the European timetable centre and on how often Eurail get updates from the European timetable centre and update their planner. I believe the European timetable centre has 2 updates per week but not all operators send or retrieve updates that often.