i need silri for the couroscant mission, and she appears to be on a rebel planet (forgot which one, at the top near dathomir) she is in the yellow heroes list on that planet, and her icon is on the map, but she is not there! the only thing i can think of is to take that planet and hope she spawns

Nope. Re load yor last save or auto-save. If you take a planet and your hero disappears, its a bug and you cant get them back. You have to reload. It has happned to me a number of times....funnily enough on both occasions I captured Honghr (sp?) I received an extra clone hero. Running around with two Emperors was sweet!