Hi @crcollver thanks for sharing your detailed thoughts and questions on the slice migration process and sorry for getting back so late to you - we had a quirk in our reply process
With this one page I've tested, is it safe to edit the JSON to match the legacy slice name or will it be easier to republish this document so that the name references might be updated automatically?
Republishing the document should update the slice ID reference following your migration (this will create a new master ref in your API which should update other occurrences also)
We don't recommend manually editing JSON models, although it is something possible to do that should also work. If you want to try doing so, it's preferable for it to happen before pushing anything to Prismic (related to that change). Doing it after the slice was pushed to Prismic could lead to unexpected side effects if you've worked with documents featuring that slice in between.
I imagine it will be much simpler to match the names of my old slices exactly so that this doesn't happen. My main question is - is this the intended behavior of the migration or is this an edge case that I may have found?
Trying to match your old slice names is a valid approach, however, it shouldn't be an issue to use other names. The API response should update once a document is published after the updated slice was pushed (again, this creates a new master ref triggering the update process).
Let us know if this helps you, and sorry again for the delay!