Pretty cool that you did this!
A few notes though…
In 1997 Disney scanned in the original 1989 final production negative used as the basis to print the theatrical release from and then touched it all up in computers and then put it back to film. So I’m not sure we can really take a 1998 print as giving us the true original 1989 look (where to find a 1989 reel though, I have no clue sadly, I also wonder if some of them would not be a bit faded by now, I forget around what time the typical print strated becoming a bit more color fast).
The colors on this seem reallllly muted. And they have sort of a drab yellow-green tint. Do you know what color space the scanner company provided your scan in? Are you really sure it was sRGB/REC709? Just comparing your scanned samples to the quick flashlight trick picks you first showed, color seems to have gone way muted. And if you swap the profile on those images to say AdobeRGB, they start to begin to look a bit more reasonable (and perhaps they were scanned in an even larger colorspace than AdobeRGB). I sort of have a feeling that you were delivered files that were not sRGB/REC709 but then treated them as if they were?
I think we forget that film could provide pretty rich colors, even in 1989. We are just so used to how faded out old prints become over time (other than for a few ones printed out on certain long lasting stock, which most were not).
FWIW, I have various pieces of what appears to be perhaps a 1990 trailer from the UK (didn’t get released there until very late 1990) for the Little Mermaid (can’t, at least not all of it, be from 1989 US trailer since one part has overlayed text about having won two academy awards, which happened in early 1990), although perhaps it is for the 1997 release, maybe some of it is even from regular release print and not all trailer, it’s a bit confusing, trying to figure out exactly what the various little set of scraps I have is from. What I have has no digital sound stuff encoded on it, just 2-track analog and it’s on some sort of Eastman Kodak stock. Not sure if all of the 1997/1998 re-release trailers and prints had digital audio encoded or whether some might still just have had 2 track analog only.
Anyway, what I have, has absolutely BRILLIANT colors and eye popping saturation. Some of her tail and some of the red on Sebastian in some frames is beyond anything seen even in any home release. I think it’s beyond what sRGB/REC709 can even display and you need wide gamut to see it all. The colors look sort of like a mix of the 2019 blu (probably closest to this overall, well the UHD even more but I haven’t gotten to compare that yet) but still clearly different, this and 2006 get her tail a bit closer to intensity although 2006 seems to make it too green; 2019 seems to often make her shells too dark and saturated though), 2013 blu and 2006 DVD and stuff simply not like any release has that I’ve seen. Flounder also has a more deeply saturated color.
Anyway, FWIW, the bits and scraps of 35mm I have for this look radically more saturated and colorful and without any hint of that drab yellow-green cast shown on the examples for the scan in this thread (look a bit closer to like your initial flashlight shots).
I have a feeling that something is off with the colors shown as examples from the scan here. Maybe wrong color space assumed or something else?
Gonna try to scan a few frames on Nikon 2000 stills scanner.