Thank you for saying this! This is the comment I always want to see on these posts and hardly ever do. I don’t intentionally study the WaniKani vocabulary outside of WaniKani (obviously I come across things when reading other materials or doing other types of study), and it’s genuinely been so helpful to me to just keep getting things wrong.
People tend to remember that with an SRS after each review the card comes at a later interval, but forget that it’s actually that after each successful review the card comes at a later interval. If you get something wrong in your review, you don’t know it well enough to move on yet, and that’s fine. It’s actually good. It means the SRS is working.