Or rather 1 bug with this ability and a 2nd *possible* bug:
1). "Planet for a Planet" is currently activating it's effect when the advent destroys an enemy planet in addition to when the advent loses a planet. This bug only occurs when the planet is bombarded to death convetionally, not when the planet is stolen with the Coronata's Repossession ability
2). not sure if this is a bug or just the tooltip not being precise enough, but at the moment Planet for a Planet seems to apply it's damage buff to all frigates/cap ships/titans/structure but not to strikecraft.