I...think you explained that in a reasonable manner.
It's FORESHADOWED a little by Stevens ability to possess the watermelon Stevens and Lars. Perhaps Rose/Pink discovered the ability to take over gem bodies.
Pink clearly has conflicts as to her Diamond identity. Her first mission was to conquer earth, and she sadly fell in love with it and the possibilities.
Pearl was likely Pinks, gifted to her by the other diamonds. Pearls loyalty to Pink>Homeworld as Pink was unconventional and allowed Pearl freedom of choice in most matters or slowly learned to. I bet Pearl knows this is the truth, and by oath or loyalty to Rose/Pink refuses to say it. They both arranged the "false death"/Pink jacking one of her Quartz soldier bodies to be free from her loathed responsibility as a Diamond.
Once Blue Diamond finds out Steven basically is the remnant of Pink/Rose, she'll break down or stand up to protect him. I think the finale will be Steven somehow liberating homeworld from its caste system and ideas on fusion/it's disrespect for other life and planets via conquering.
Y'all must admit Steven would need some political dewey power to do such a thing, because as much as the Crystal Gems be kawaii and the Jasper, Peridot, Lapis being potentially wonderful allies. That is not enough to rapidly change a society.
Btw is the chest in Lion locked? Or is there anything unusual besides Steven finding a bubbled Bismuth?