I'm sorry but 定 's radicals are just wrong

Sure, these are similar looking but not visually the same 疋 vs 定. Their building blocks simply differ.

I’d say you’re overthinking things. Knowing radical names isn’t important in the long run, recognizing them as components in kanji for guessing the correct reading/meaning of specific kanji is. But, in the end, you’ll just look at a kanji and “know” its reading and meaning, no further analysis or breaking it down into components.

Especially in the case of WK, where radicals are not the official names, but just tools for memorization and creation of mnemonics, it’s not meaningful to put too much energy into learning them I think. They’re initial stepping stones.

I highly recommend the Keisei-script as it really helps in the upper levels with recognizing radicals and their relationship to readings. This is highly useful and gives you a different path to memorizing readings than the WK mnemonics that gets increasingly convoluted in the upper levels due to the many constituent parts of complex kanji.