Yeah my current approach for programmatic Anki notes is genanki + using a stable ID as the first field of cards to allow for updates. Great point about ephemeral sentences -- something for me to think about creating an auto-suspension add-on for (I've seen the same issues about memorizing structure).

What did you use for scheduling? I've seen ebisu [0] used before but found it difficult to grok. I can say as I've used FSRS [1] within Anki I've started to like its decisions alot.

I think the main thing that keeps me from rolling my own Anki is mobile support. I had an Android app once and having to keep up-to-date with all the changing App Store requirements was annoying as hell. Eventually they took down the app for some compliance thing.

[0] https://github.com/fasiha/ebisu [1] https://github.com/open-spaced-repetition/fsrs4anki