EMH: "Is the Federation at war with the Romunlans?"
EMH Mark II: "No, the Romunlans haven't gotten involved with our fight with the Dominion."
EMH: "The who?"
EMH Mark II: "Long Story."
The Jem Hadar
The Search happened before Voyager even made it to DS9.
So, you expect all characters to know everything all the time. Does that really seem reasonable or realistic to you?