I think we're using 'stress' and 'tones' to refer to completely different things. I think you're using 'stress' to mean something like what I would call 'focus

I think we're using 'stress' and 'tones' to refer to completely different things. I think you're using 'stress' to mean something like what I would call 'focus prosody', and you're using 'tones' to mean what I would call 'stress'. But, in terms of the acoustics, 'focus prosody' is closer to Mandarin lexical tones (though not in function).