Nice stuff.
Looking at the frame though, the detail lost in the door trim might not have anything to do with Lowry.
Measuring that door frame @ 1080P there are very few pixels available to convey the detail (4x less than at 4K), and when you factor in dropping to Bluray standards (8bpp and 4:2:0 chroma compression and h.264 compression) this is exactly the sort of detail that would get smeared out by the lower resolution and BD compression rates.
Not defending Lowry et al. but the loss of that detail could just be down to the limits of BD especially if there is gate-weave giving the compression algorithm headaches.
It would be an interesting experiment to take 20 frames of that sequence from your scan, and compress it to BD specs and see what is lost even in the most careful conversion possible.