Hi! I'm fairly new here, working on 200D, so I'm not too sure about anything either. However, I think the best way to share code is fork the Hudson repo and work on your fork. When it gets to a useful stage, it can be merged back in.
My guess would be that QEMU is failing because of some hardware in the 80D that is not yet emulated (eg, some flash ROM, or a secondary processor). I don't have enough experience to diagnose beyond that, and I could easily be wrong. There are other threads about how QEMU was made to work on older hardware, which might help.
You could try building with CONFIG_HELLO_WORLD set - I've been told this is a simplified build. Using less functionality means if you do have some stubs wrong it may not hit them. I can build this but it doesn't boot for me. Another approach that I have started trying is using digic6-dumper, and calling one untested stub at a time, to see if it crashes horribly.
Are you able to compare the stubs you've found with roms from a different camera? From what I've seen, it is often fairly clear when you have it right (especially with a decompiler, not just a disassembler - Ghidra gives you this for free, if you don't have access to IDA).
The 80D is fairly close to the 200D - maybe you could help me? I have found almost all of the stubs I need, but can't find any of the EDMAC functions. If you can share any addresses with me that would help a great deal.