I used to talk to her on Skype for the last three years she was alive. The second dubs of the DiC Sonic shows were DVD only at shops like Akihabara. She knew fluent English and she doesn't like to reveal her face. In fact, she never has. Her best friends Emiko and Memphis haven't, either.
A few days ago, I was messaged by her sister who claims they dubbed a few episodes of Sonic Boom into Japanese as well, but they weren't massively released on DVD in shops after Youko died. A re-dub of the Shadow Saga of Sonic X was unreleased. Junko claimed Youko voiced Shadow in those. Just like her sister, Junko doesn't reveal her face, either.