So here I am, writing up a blog post, about this topic among others. As part of that, I reviewed the diff, and despaired. I finally understood why the new descriptors work, and why the old ones did not, even though the report ended up being the same.
All this work, all this diving deep into the spec, was all for naught, for the real fix is changing two lines.
See if you can spot what I saw: https://github.com/keyboardio/KeyboardioHID/pull/19/files#diff-482271719524cbe1a76840487519b299