I'll be looking at this in detail. I've started a company to do similar things, https://6k.ai

I'm currently concentrating on better data gathering for low-resource languages.

When you look in detail at data like Common Crawl, finepdfs, and fineweb, (1) they are really lacking quality data sources if you know where to look, and (2) the sources they have are not processed "finely" enough (e.g. finepdfs classify each page of PDF as having a specific language, where-as many language learning sources have language pairs, etc.