I'm only 15 years late, but I translated this interview from the 2004 book "Aya to Ayaya."
I do believe it's the most in-depth interview of hers I've ever read.
Check it out if you'd care to!
Matsuura Aya “Aya & Ayaya” interview (Part One)
Matsuura Aya “Aya & Ayaya” interview (Part Two)
Matsuura Aya “Aya & Ayaya” interview (Part Three)