"Flat" for stills involves shooting raw, and making sure all of the extra settings (auto-light optimizer, noise reduction, etc) are turned off.Aren't those settings affecting only JPEG preview of the image? Could someone confirm what settings affect RAW files (I assume, HTP)? And do those settings (Picture Style, Noise Reduction, Auto-Lighting Optimizer) affect the initial image you get when you open the RAW file in LightRoom?
I think only HTP and black frame subtraction do anything to the RAW file maybe other than tagging it with some settings.
I have no idea why anyone would want cinestyle for stills when they have raw or even neutral jpeg. Cinestyle for video was designed to fit into a log-based workflow, NOT because it has more dynamic range. And it looks really bad out of camera and tonality is generally worse once graded than material shot with the neutral mode. The proper answer is just control your light better. If you need that much dynamic range to capture the scene, you're probably going to get a flat image, which is a major problem because screens and paper are low contrast, or you'll have to use HDR or something tacky. Just light correctly or, if shooting landscapes, wait for good light. It's hilarious to me that DXO mark's "landscape" metric is measured by dynamic range...most good color landscapes are still shot on Velvia (four stops of dynamic range); even zone system, the first real HDR technique, is only ten stops!