Star Lord is a famed hero, and Kree care about warrior heroes. And the Skrull's intelligence network is expansive. They are, after all, Skrull. Such information is freely available to the Supreme Accuser as it might be useful in the execution of her duties.

[Aka someone is a fan and went into the secure intel records to find out more about the Guardians. Also... being the Supreme Accuser was no small thing as he would well know. Hers was a high position in the Empire.]