Quoted from Sprout:but it still begs the question of why I'd see differences between these three different 5200's on the same board, with the same resistor configuration.
barakandl noted some time ago that a tube of NOS TMS5200 chips with the same date code each produced different pitch in speech. So what you're seeing probably isn't unusual.
https://pinside.com/pinball/forum/topic/flash-gordon-wrong-speech#post-5351112