I think your macro lens scan look pretty decent, certainly good enough for forum posts.
I don't use a calibrated screen or anything but they all seem to have a cast of some shade or another.
Besides dust/scratches I personally want to reproduce the frame exactly as it is, even if it is unfaithful to the scene, I like that uncertainty of perfect reproduction that characterizes film, I mean, nobody shoots Velvia with the intention of de-saturating in post.....or do they...I dunno..
To cut to the chase, if these frames do have a cast in your hand, I'm fully supportive of not changing that, they are what they are and to hell with adjustments.
If they don't then it could be my screen, or yours, or your choice to have a cast..