It was never supposed to be nonsense. To anyone playing in Japanese or presumably other phonetically consistent languages, it's obviously a sped up, slurred/somewhat mangled version of what the text is saying. I guarantee not a single Japanese player didn't notice this, or otherwise thinks it's pure gibberish. Japanese is not my native language and I noticed immediately; any native would have too.
The problem is that English is a phonetically inconsistent language, with a massive number of rules required to even begin to approximate the mapping from text to phonemes (and zillions of exceptions). So this kind of really dumb TTS not intended to be actually intelligible doesn't work at all in English. And so it sounds like actual nonsense.
The problem is that English is a phonetically inconsistent language, with a massive number of rules required to even begin to approximate the mapping from text to phonemes (and zillions of exceptions). So this kind of really dumb TTS not intended to be actually intelligible doesn't work at all in English. And so it sounds like actual nonsense.