In my experience, most of the un-romanized artists are just typos or erroneous romanizations provided by the booklets. It's easy to confuse some kanjis (yeah, even for japanese people) and is not that uncommon to see mistakes on the album's credits.
Anyway, aside from the reasons above mentioned by CHz, in this
album Yuriko Mori is credited along Masatsugu Shinozaki, Kiyo Kido and Masami Horisawa (all of them are credited on
Bamboo Blade). Furthermore, in every other Yuriko Mori credited album, you know who is also credited, Masatsugu Shinozaki.
Sometimes with a little of common sense is enough.