This looks very much like the Keisei semantic-phonetic compositions patterns. They work great when they work but there are limitations.
- You must beware of the exceptions. Some kanji fit the visual pattern but use a non pattern on’yomi.
- On top of that this works only for on’yomi. When wanikani teaches you the kun’yomi as the main reading the pattern is not so helpful for Wanikani purposes.
- Moreover there are sometimes parent kanji with more than one on’yomi readings and the children use different on’yomi. You have to remember which on’yomi is used in each child.
Despite all this semantic-phonetic composition works well enough to be useful. You can get these patterns from scripts such as these two below.