Advanced Japanese Learner--how long would it take me to reach the last quarter of the course?

I’d highly suggest Houhou! It’s an SRS application that works very similar to WaniKani. You’d have to come up with your own mnemonics, but you can add kanji and vocab at your own pace as opposed to being on a set course you already know most of. It’s really useful for when you really like WK’s style of reviewing but the actual content isn’t what you need.

All the radicals are listed in the kanji page and every kanji has the radicals used in it listed on its page. You can use that to help you learn the radicals and start looking for them in the kanji you’re learning c: