My opinions so far is that campions act like bogling seeds. Its completely random what the campion flowery crossing will produce. I've gotten ferns, rushes, prickly pears, pampas, pony, and bulrushes and even flowery cactus. Thats just from the ones i DID ID. I dont farm the poppy dust seeds as much as i should. Things like poppies, lillies, and snowdrops might act completely random as well, i havent gotten a lot of those to test it on.
As for the bonsai/flowery crossings, i've crossed several of the rectangular type, and crossed a purple spider to a purple bonsai so in three days i'll post my findings. Hoping its not just a certain 'type' of bonsai that will successfully cross more bonsais.