You cannot guess the pronunciation of a character from the way it is written. At most the "phonosemantic compound" might provide a clue to possibly reduce the space of possibilities.
It's not pedantic in that the characters themselves really are sound-based and provide a pretty decent clue. That said, it's still just a clue, and there are multiple similar pronunciations associated with any phonetic component, so it's still guesswork in the end.
And so we are back to square one: it is not possible to know how to pronounce a character by looking at it (and any clues are not "decent" in the majority of cases), as opposed to alphabetic systems...
You cannot guess the pronunciation of a character from the way it is written. At most the "phonosemantic compound" might provide a clue to possibly reduce the space of possibilities.