Since when does FLAC run a lossy pass? You can recover the original soundwave from a FLAC file, you can't do the same with an MP3.
I'm pretty sure FLAC does not run a lossy compression pass.
Flickering textures in game engines are likely due to z-fighting, unless you're referring to some other type of flickering.
If you're looking to preserving as much detail as possible from your masters then floating points make sense. But its really overkill.