Thanks for sharing your code, I’ll have a look and try to compile it as soon as I manage!
Meanwhile, since you own a Nikon camera and you are interested in having a “quick starting point” for your edits, you might be interested in this other answer where I give a couple of resources that explain how to precisely match the in-camera Jpeg colors and tones using free RAW converters: Can I match RT to out-of-camera JPEG - #5 by Carmelo_DrRaw