Some things that may be of interest. First relevant to the posted article:

A site that has used neural nets to classify go moves that good players would probably make that weaker players (of varying ranks) would probably not: https://neuralnetgoproblems.com/ (code available on github)

https://ai-sensei.com/challenge (behind login wall, and in future possibly a pay wall) is a similar idea, but the difficulty of evaluating the position is determined by how users of the site perform in practice.

And more generally, but relevant to your comment:

Players can play humans at an appropriate rank on OGS https://online-go.com/ (not as popular as the Eastern servers, but probably popular enough) -- or against calibrated rank "human-like" AI players by painfully setting up the right katago models themselves, or by paying for a subscription on ai-sensei.com

A go education site that's currently largely by and pitched at Westerners: https://gomagic.org/ for leveling up from the basics.

And a lot of books are now available easily and electronically in English (and some in German): https://gobooks.com/ --- I'd recommend "graded go problems for beginners", "tesuji", and "attack and defense".

Some good sites aren't (fully) available in English, like https://www.101weiqi.com/ -- but there are chrome and firefox extensions to translate just enough of it to make it usable.

[To help search engines: go is also known as weiqi and baduk]

Thanks for the first link it's really fun game :)

I've been playing lots on OGS (with my friend in particular), under my pseudonym erelde