Some things to be mindful of. When using a splitter, only one fan reports back the speed for PWM control. Meaning, if you mix types of fans, the rpm of the one connected to the 3 pin side of the splitter will seen by the motherboard or AIO. All the other fans will just run based on a percentage of their overall speed. I've seen instances where some fans can run at lower rpm's than others which cause some to not spin while other chained do. Personally, I'd set a different fan curve for the case fans as opposed to the AIO ones. The AIO should be based off coolant temperature where the other ones have to account for moving all the hot air, including GPU, out of the case.
Also, Corsair uses a custom RGB connections which means you need their propretary controller. I'm assuming that's what's built into the case. If so, they that can serve as your RGB controller.