On style tests and comparisons, I’m working on some changes to Citeproc Test Runner that may be useful. An outline of the plan is in the dev section of the Jurism docs. Basically, the plan is to set up style-specific collections in a public Zotero group, and dump tests from there into eponymous subdirectories of a GitHub project that houses style tests. The dumped fixtures will then either be approved as valid using the Test Runner, or manually edited in the RESULT field to reflect desired output.
An additional part of the plan, not reflected in the Jurism docs note, is to output each form of the item: initial reference; ibid; subsequent; and !near-note, each with and without locator, plus the bibliography entry if applicable. That should give a pretty good picture of what a style does; and by running tests for one style against another, you can get an at-a-glance view of the differences.
I need this for Jurism development anyway, so no funding is needed to push it along, but someone might be able to build something interesting on top of it for use in CI or so.