And would that really help? We know that the travelers have been here for several months now. If you were seeing a nightmare repeat, with no way to interact with anyone, exactly how long would it take before any of us stop believing that it is even possible to change anything? As far as Nagato would know in this scenario, Pearl Harbor is happening again, and nothing seems to have changed. The only reason the USN ships even kept trying was because they knew it was possible. Nagato does not have such an advantage.
EDIT: Thompson had newspapers to see the butterfly, Nagato may as well be in a sealed box...
Well, if I were Kancolle
Nagato, I would be doing my best to interact with anyone to try to derail what is to happen. Any future-Nagato would know that interacting with humans is possible since she did it in the future. Note, this does not necessarily mean 'appear in front of Admiral Yamamoto', it could be done by using her communications gear to send out a 'hey we need to talk' message similar to the one Bismarck gave to the RN battleship. She also could presumably talk to other ships (
Mutsu certainly) and try to work the problem from multiple angles similar to the shipgirl conspiracy in Pearl started by
Utah to get lines of communication to their crew/commanders.
Presumably she would also have access to IJN data, being the Combined Fleet's flagship so would be potentially 'in the room' for planning sessions, intelligence briefings, and so on. Some of which would reflect changes in the timeline such as
Hood not being sunk, Taranto's date changed and so on.
Now, all this said, I doubt that this Nagato is a time traveler from the future.
We have one known data point of divergence for Japan (Pearl Harbor being hit a week early). This makes no logical sense if this is the actions of a time traveler, since the time traveler would insist on sinking the USN carriers, and on November 30th,
Saratoga's well clear of Pearl coming out of her refit in Puget Sound,
Lexington is getting her 8 inch guns removed, and
Enterprise would be away delivering fighters in OTL.
Now, it is certainly possible that the IJN got bad intelligence on ship movements, but I have a hard time buying that the Japanese would miss
Saratoga's scheduled refit which puts her out of the area where she can be attacked for several months. Sara being refitted means that if Pearl is hit, you will have at least one intact carrier in the Pacific after the attack (since it can be assumed that said refit will be
massively expedited to get her into action). Now, for the IJN battleship admirals, one more aircraft carrier available means very little since the US Pacific fleet's battle squadrons are ravaged in preparation for the fleet-on-fleet Decisive Battle ala Jutland or Tsushima. For any time traveler like Schreiber or Thompson, they would know that the carrier was the key piece of Pacific War naval force projection, with the US battleships being very much secondary.