Indeed, the scans might be perfectly done, but as we cannot see the negatives, we must consider issues in every link of the chain. That being said, the negatives look old and deteriorated and if they are, a positive scan (that provides a negative image) might provide a better starting point. In order to find out, @Push9797 might try to get positive scans that we can compare.
If the original shots are transparencies (for projection), a negative conversion could help too, according to this post/thread.