I'm responding primarily to bump to those with greater expertise, but I will say that wildly scattered scores are pretty normal around here. That extreme unevenness probably brought quite a few of us to this board seeking help. So welcome!
I'll leave interpretation to real experts (whatever would we do without aeh?), but I will just note that my kids have many similar extremes, including one with an even larger working memory/ processing speed split (but in the opposite direction). I'm guessing yours can use that amazing processing speed to compensate for a whole lot of things, and will hook into other kinds of memory to do certain kinds of tasks.
My DD (who is dyslexic and ADHD) also had wildly divergent memory scores, depending on what exactly was being tested. My understanding is that it's pretty common for kids with ADHD to be far better at retaining meaningful information (like story details) than disconnected data, and we could certainly see patterns of notable strengths and weaknesses across her results. If you want to dive into the memory weeds, the first main section of the Eides book reviews many types of memory in detail, what they do, what it looks like if they are impaired, and how to compensate. It's fascinating (albeit like reading a dictionary), and available in a lot of libraries (
https://www.amazon.com/Mislabeled-Child-Solutions-Childrens-Challenges/dp/1401308996).
