Indexing expertise needed for the User Guide

We've been working on creating a User Guide -- the project page is here:
https://www.drupal.org/project/user_guide

One of the things we decided early on is that it should have an index. So, as the topics were written (by a variety of people), each one was given one or more index entries. This has resulted in an index that is sort of OK, but has some problems, because it was created by many people instead of a single professional indexer. You can currently see the index (as it is now) at:
https://userguide_new-drupal.dev.devdrupal.org/d8guide/en/_index.html
(user name/password: drupal/drupal)

We already have an issue open to do some basic copy editing on the index, such as consolidating near-duplicate entries and standardizing on "Block" vs. "Blocks":
https://www.drupal.org/node/2699833

But it would really be helpful to get the assistance of someone who has some real professional expertise in indexing (which I understand is quite an art!) to help us with either some guidance on how we might improve the index, or some direct indexing help.

So... If anyone subscribed to this group has some professional indexing expertise to offer, please either post a comment here or contact me. Thanks!