The best resources I found weren’t twin-flame-specific at all.
You don’t really need anything with the terminology.
Eckhart Tolle’s “The Power of Now” is a great place to start. It changed how I understood a lot of what was happening during the intense phases.
For inner child stuff, which is where a lot of the work happens, John Bradshaw’s “Homecoming” is solid. Goes through each childhood stage and what you might have missed developmentally.
I would stay very far away from anything with “twin flame” in the title.
I don’t think there’s anything out there at the moment with any value and the big one you’ll see ads for are from the twin flame universe cult stuff.
If you want something a little more story-based, I see this one popping around the place, but I think it stays in the shallow end. Maybe something for some light reading: