The 2017-05-18 update of JLS 6.5.3.2 introduces the concept of unique visibility, but still has this unchanged sentence:
"The package name Q.Id names a package that is the member named Id within the package named by Q." If "the" in "the member named Id" is to be taken literally, then the specification still doesn't work, as I may elaborate if needed. But I assume, dropping "the" in favor of "a" or a similar change easily fixes this to reflect the intention, right? Stephan