That's what I find outstanding with Sandris units. He manages to get the proper level of details, so they llok good at civ scale.
One thing I notice is that he removes unnecessary details, like having a very simple face.
Perhaps you can try something similar : removes the smallest details, exagerate a bit what you want to show.
But anway, I wouldn't mind to much if I were you, your latest units, with improved run and death animation, are really good, and we can recognize the details.
It may also come because you make "too many" units. When you 4-5 camo versions of a guy with the same weapon, and 4-5 combination weapons for the same camo, and the end you have some similarities.
That's when you have to pick some that really make a difference.
Like use the k98 + feldgrau simple uniform for 1939 German, then the Stg44 + camo for 1945, and you can really tell them apart.
But if you put all your german units, then you'll see similarities.
ie: Difference is clearly visible
Here it's not so obvious
Personnally, I don't try to use all your units. I select within the large choice your provide us with the one that I prefer, and I keep only the one which are different enough.
I think your series are great as they allow us to choose what we want, but the side effect is the tree is hidden in the forest.
If you made only one unit for each weapon, with an evolution of the uniform (rifle + non camo, SMG + camo for instance), you'd see more difference.