I know redfur files are like config files for HairWorks. They can be used to disable/nullify parts of HairWorks. For example, the mod "HairWorks on everyone, but Geralt" is done by disabling HairWorks for Geralt through redfur files. Then, if you enable HairWorks all the way (highest setting of 2 I think), you get HW on monsters, horses, but not Geralt. The same can be done to parts of Geralt. For example, I use a mod that disabled Geralt's HW Hair, but not the Beard! The result is awesome because, much better than HW hair on Geralt with pony tail haircut.
I think the same files have other configuration properties, like adding wind influence, but alas, I could not figure out where such settings are located. Normally, you can simply add "windInfluence" parameter to FX w2p files, but not with redfur files. I think redfur files are also responsible for HW quality, interpolation, etc. I mean its RedFur - Red because of CDPR and Fur because of HW (yes, today I am Captain Obvious)..
Excellent mods here - https://www.nexusmods.com/witcher3/mods/2123/? - enable wind effects on animals' HW . You can try to compare that mod's redfur files with vanilla ones to find out what changed
I think the same files have other configuration properties, like adding wind influence, but alas, I could not figure out where such settings are located. Normally, you can simply add "windInfluence" parameter to FX w2p files, but not with redfur files. I think redfur files are also responsible for HW quality, interpolation, etc. I mean its RedFur - Red because of CDPR and Fur because of HW (yes, today I am Captain Obvious)..
Excellent mods here - https://www.nexusmods.com/witcher3/mods/2123/? - enable wind effects on animals' HW . You can try to compare that mod's redfur files with vanilla ones to find out what changed