If there is a mechanism that satisfies one of these, there is a mechanism that satisfies the other, because the UA can infer meaning from pronunciation and vice versa.
merge these two clauses
There are many examples where knowledge of pronunciation are not sufficient to provide meaning. For Japanese, meaning issues are not always the same as pronunciation issues. The meaning is needed for words or phrases which are unfamiliar to the users even if user knows the pronunciation/reading. And the pronunciation is needed for Han characters, especially for proper nouns such as the name of a person or a place. There are also unfamiliar Han characters which are difficult for users to read. Additionally, Japanese screen readers can't read some Han characters correctly in some cases as the Han characters have multiple readings in general.