My two cents: the English meanings would probably feel like a huge waste of time. Your friend would probably only need the reading reviews. (I’m assuming, of course, that your friend’s knowledge of meaning and nuance in Japanese is at least on par with what WK presents.)
WK isn’t necessarily going to be useless though: I have a friend who’s a native Chinese speaker, but he can’t read at all, and I can see how much trouble he has with characters. Having something like WK to encourage structured, regular practice is probably going to be helpful. However, I don’t think it’ll be very useful beyond the intermediate level, unless your friend doesn’t intend to do much reading. The reason is that I think that someone who’s fluent will be able to make guesses and fill in the gaps from context once they’re able to read enough to understand most of a sentence.
(For what it’s worth, one of my favourite VTubers is kinda like your friend – very fluent verbally, even sounds native, but not that great with kanji. From how she approaches reading text with unfamiliar kanji and compounds though… well, it definitely feels like she defaults to words and readings that she’s familiar with, and she only really gets stuck when she sees kanji she doesn’t know anything about at all. She can easily read scary-looking kanji in words like 響いている, probably because the word is common, but she gets stuck on rarer words containing simpler kanji. I’m expecting it’ll be the same thing for your friend: with roughly intermediate kanji knowledge and fairly regular reading, recognising common words in their kanji forms should become easy for your friend, but rarer words will require further study. If your friend intends to read a lot, those words should be acquired in due course; if your friend tends to do much more listening and speaking, then maybe WK will make up for the lack of visual practice.)