I asked about the "system" for reporting errors. I was told that I should email/contact the Associate Media Editor for Mathematics and Statistics who sent us the collection. So that's what I've done. Repeatedly.
If there's a "dynamically-changing database" then that's news to me. I receive a return email with an apology and a corrected .pg file attached. In some cases, the corrected file appeared to be nothing more than the patched file I sent when I reported the error---and my patches are not always the "best" way to fix the error, just quick.
In any case, we can't wait days for fixes to buggy problems. Students and instructors lose faith in the entire system.
About the wording of the problem that I included in my first post. The analog in the textbook seems to be: "Find the volume of revolution about the x-axis for the given function and interval." Still not as good as it should be, but at least it doesn't refer to an unbounded region.
Calling these problems "quality assured" is, in my opinion, false advertising. I've spent precious hours responding to puzzled students, fixing bad problems and trying to reassure colleagues that WeBWorK and Rogawski's text were good choices for our department.
Thanks for your reply.