I’m not trying to hate on KaniWani, but pretty much any E->J solution is, at best, a stopgap measure in my eyes. Even with the help of sample sentences and dictionaries it’s difficult to pick up on natural usage of words when learning in that kind of environment. The synonym problem on KW is a pretty good example of this. English has a ton of similar words as well, but most of those have a specific intonation, period, or usage case.
There are other tools like hinative, italki, lang8, ect. that all let you practice forming complete Japanese (at your own pace) with native feedback, so I think it’s a little better to consider doing that instead.
The WaniKani experience has been exactly what I expected from using it. It’s a great tool for learning to read [kanji]. If I had any problems in the process it would be with my shortcomings as a student. (I would appreciate getting more general/kana vocab and common names under a related system, but I’m not allowed to complain about that until level 60).