Delenn would have known perfectly well who Sheridan was. The Minbari were aware that "Starkiller" was part of the peace mission. Of course she would take great pains to hide the fact from everyone on B5, especially Sheridan, just as she concealed her prior acquaintance with Kosh in The Gathering. (Apart from a slight slip during the reception at the end. Look at how she reacts to Kosh - very different from the way everyone else is behaving. She knows something about the Vorlons that the others don't, and JMS made sure he dropped this tiny hint at the very beginning of the show.)
I doubt she would have recognized either G'Kar or Franklin almost a dozen years later. They were an anonymous Human and Narn to her, and she didn't see them for more than a few seconds, and that from a distance.
Regards,
Joe