I think you underestimate the value that creating the cards individually provides. For me the first learning step is the way I create and structure the card, think about mnemonics, add a photo e.t.c.

Mochi is a great help there, since it provides a lot of small conveniences especially for language learning. The ability to automatically add a translation and spoken pronunciations is super nice and built in a way that it seamlessly integrates into the keyboard-centric markdown flow of the app.

IIRC Mochi is written in ClojureScript and it shows, it's a really simple, yet composable and powerful tool.

The author also keeps polishing it continuously, which I found to really streamline everything.

It's my absolutely most favourite tool for learning languages, because it does its job beautifully, efficiently, and doesn't get in my way, and that's a property that's hard to come by in software these days.