The Aurora Class Tracking System.

[Forgottensmoke]

First would they not be able to track the Travelers as almost all Aurora class ships have been destroyed and since they only have 4 ships now (1 was destroyed in the battle against the replicators) they would notice there was an extra ship (Dr. Weirs)? Shouldn't they have checked if any Aurora Class ship was not on location at the time when they attacked the replicators and they would have went after Larrin's ship as it was on its own because all replicator ships were at their home world and a liable target which could have been easily destroyed.
so they could have went after Larrin's ship and the rest of her fleet

I know its a bit hard to understand but think about it, they will notice that their are still too many Aurora Class ships left in the galaxy

[2ndgenerationalteran]

The Core Drive thing was only to track Oberoth's Aurora's not original lantean Auroras or any other Auroras made by non Oberoth-supported factions. So Larrin is free to roam just like Wier. If the original database could detect all Auroras we would have found Larrin's Aurora Long ago. And we dont know how many Traveler Generational Ships are left when they departed to Asuras i counted 6 TGS entering hyperspace and when falling back i counted only 5. But that only includes the captians of the ships that agreed to fight.