When I did my first book (self-published through Amazon by the author), the author put in the text themselves, but it didn't look as good as it could have. The second project I did with the author, I offered to do the typesetting myself in InDesign. MUCH more difficult. While I'm glad the author gave me an increase in pay (and was happy to do so), adding the type myself was hard and tedious. I wish there had been an opportunity to work with a graphic designer to help with the text rather than my doing everything myself. On the one hand, I felt more in control over the quality of each page. On the other hand, it increase the stress of working on pages (and I had the lovely task of having to fit both English and Spanish translations of huge paragraphs).
So I'd say, if you haven't discussed text, and especially if it's not in your contract, politely discuss this with your client. Hopefully they'll be understanding.