My comment above was the most I've ever written about how it works, except for one very long comment in my database migration code, which I had to write to remember how it's supposed to work.

I created the GUI in Qt. It's not beautiful, but gets the job done. I decided to finally open-source my WIP and put a screenshot in the README: https://github.com/Yorwba/alphabet-soup

The comment on database migration is here: https://github.com/Yorwba/alphabet-soup/blob/4f68057ed5d7dbf...

If you don't care about all the Japanese-specific stuff, you could try running make data/tatoeba_sentences_XXX.csv where XXX is the ISO 639 three-letter code of the language you're interested in. That collects all the sentences in that language contributed to Tatoeba by native speakers and puts them into a TSV file.

Thanks!