Hello
I have not yet enough experience to offer suggestions. I have bookmarked “Digitizer’s” responce in this thread. I have not sot film for more than 25 years now, though I have boxes of negatives of missing or damaged prints from years ago. I use digital cameras now and an x-rite color checker card sometimes if accurate color is important. I’ve not yet had serious problems digitizing color negs with NLP. For those still shooting with film I wonder if using something like the color checker could be a fix. So I searched the forum and found this comment from 5 years ago. I’m suggesting it’s use with at least one frame to get close. Sure color changes thru the day and with each film stock. It won’t help me, digitizing old film!
X-Rite Color Checker Passport: Calibrating Camera to backlight - #6 by GeorgeZenko