As the OP mentioned, however, it is easier for them to use practical examples (like the vocabulary) in order to remember the Kanji. As I literally NEVER use the WaniKani mnemonics, the vocab is my primary method of remembering readings. Of course, my experience is largely built upon the fact that I have a wide vocabulary of spoken/heard Japanese, so it’s more likely than not I know words that use the readings.
I can’t agree that they are a different set of material, as they wouldn’t be included in the lesson portion of of the Kanji if they weren’t meant to be linked. For English meaning, I agree more that Kanji should be used more as a reference point than a direct correlation, but, for readings (outside of the army of exceptions), it is incredibly important to NOT separate the Kanji from its vocabulary. If that were the intent, we’d always learn the Kun’Yomi with with Kanji rather than usually learning the On’yomi first.
I think it’s very useful and quite fine to have examples that use the other readings, but the OP was simply requesting that at least one example match, not that all of them match. If you have no matching examples, you’re effectively teaching a non-English learner “Two” for the Kanji and giving them only “Bicycle,” “Binary,” and “Diatonic.” It’s nice to know that it will do strange things, but it does absolutely nothing for the purpose of reinforcing the given reading for the Kanji, which is what you need to remember to even unlock the vocabulary.
Thankfully, 生 is an abnormality in how many readings it has, compared to the norm, so this normally shouldn’t be a problem. Most Kanji default to one Kun’Yomi and 2 On’Yomi, meaning it’s unlikely an example containing the Kanji reading (normally the most common) won’t be listed. 生 has the unfortunate circumstance where only 1 of the 5 vocabulary in its introductory level use the given reading, whereas 22 of the total 43 vocabulary containing the kanji use the same reading.
Maybe I’m weird, but I see the lessons as being fairly useless overall, as I always take time afterward to view the Kanji page and search it on Jisho if I am not familiar with it already (I also practice writing, so stroke order is necessary if I can’t guess it immediately). So personally, it’s small requests like this that are my favorite to see.