This is a case I don't think I've ever encountered.
If I read this correctly your spokes have been pulling free from the hub and not the rim; and, there is no breakage, just a free spoke flopping around attached to the rim. Yes?
Unless I miss my guess, there are inner and outer spokes with differing angles from the butt end. At least that's the case with the vintage wheels I just re-laced, inner-outer and left-right for a total of four angles. I think maybe you have a pair of wheels that are laced inside out and that's why the spokes are popping free. I'd check the butt angle first and see what's happening there, then if my guess is right, you'll need to have the wheels re-laced properly.
