My idea for a Blue Seal change would be that it is changed to a chance it gives you a planet card of the played hand based on the number of scoring cards the final hand had.
The chance would be (number of scoring cards)/5, meaning that a Pair would have a 2/5 chance to give a planet card per blue seal, while hands like full house, full flush, or a full straight would guarantee a planet card.
Jokers that affect the number of scoring cards will affect this chance, like a High Card with 5 selected cards and Splash Joker would be guaranteed while a 4 card straight with the Four Fingers Joker would be a 4/5 chance.
Likewise, any retrigger Joker like Mime will retrigger those chances and Oops! All 6s will double the probabilities.