As the title says, switching the drop locations of these frames seriously needs to be done. It just makes sense. Make the water frame drop from the water/submersible planet, make the frame with day/night modes drop from the only planet with a day/night cycle. Why does it not already work this way? Could even have the drops for her parts correspond with the day/night cycle, which would make it less tedious.
I mean, Saryn drops from a Grineer colosseum, Atlas drops from the Infested space ship monster, Mesa drops from the Infested grofit conversion failure.
The Warframe as a boss drop usually makes zero sense and the whole system should be reworked. You should get weapon parts from the bosses and get Warframes from quests, Syndicates, and specialized game modes (Mirror Defence for Citrine for example).