I'm glad you aren't smelling ammonia, just an earthy smell. If the air in the coop ever seems unpleasant to you, definitely adjust what you're doing right away. Before we got all this warm weather and humidity, did the air in the coop feel humid like walking into a greenhouse? Or not too different from the outside or a house? That's one way to kind of gauge how your humidity is and whether you need more ventilation.
Finished compost from a compost heap is dark and fairly fine. It's usually more fluffy than what you have, because most compost heaps are stirred regularly, to give the aerobic microbes in the heap plenty of air and increase the rate they are breaking things down. Plus it keeps the microbes and their food source more evenly distributed, as they work and multiply. You get compost faster that way. In your coop, you've also had all your chickens walking on it all winter, compressing it. Parts of your litter probably looked a bit more like chunks of compressed particle board, only darker. That may be some of the litter that's 8 months old and microbes have had a lot of time to work on it, starting well before the cold weather hit.
You can run compost heaps hotter or cooler, depending on the ingredient mix, the moisture and how much air (turning) you give it. Each has it's advantages. You can do the same thing in a coop. In your case, using a little more of the shavings, compared to the amount of chicken poop, would slow it down some. I usually run mine cooler and slower than yours, then finish it in a compost pile in the garden. I even run a large cooler pile in my garden, since I'm not in a hurry and have lots of acreage. Even with no effort on my part, it will turn into compost. We always have a huge leaf pile, too, since we're out in the woods. Hot piles are more work turning, but good for eliminating weed seeds and disease.
I think you're getting a rate of composting activity in the coop that most people don't see. I wouldn't run it any hotter than you are. I'm not sure what others that run their litter warmer than I do will have to say. I'm torn between having you be careful not to get it any hotter and being really envious!
Have you been turning it at all this winter? Or mainly just surface dressing it with fresh shavings? I've done it both ways.