Alright, that was a tad long. Here's the shortest feedback I can give. Thesis: the prime use case for the index is looking up commands and events. See my long reply for why.
Usability baseline: an index page with links "A", ... "Z" at the top, each linking to a flat list of commands and events starting with that letter, in case-insensitive alphabetical order. The longest list is "Q": 83 entries. Most lists are 20 entries or less. Whatever index page design we choose, it should not be substantially worse in usability for the prime use case than this baseline.
