Very impressive indeed, so much to like about this. You say it’s still in progress so forgive me if these suggestions are already in train:
When you’re so realistic already, the uniforms just cannot be glossy & have to be matted/flattened. Not sure what happened to the ranging poles (they seem to have received a big spray of too-red camo) but they should be painted red & white (from memory) 50cm (1:1) alternate bands – easy with masking tape. The tracks should at least have a rusty wash on them and a mud wash on top of that, along with the wheels. I’ll stand corrected – I know many photo refs don’t show this – but I would think there has to be a rolled-up tarp hanging off it somewhere as basic protection against the elements.
Excellent photography, great build, it really deserves a bleak diorama base with some spent shells lying around