What does WER/CER stand for? I see it as some kind of key metric under each model but not clear what it's measuring

Word Error Rate and Character Error Rate.

Common metrics to track how coarsely or finely accurate voice AI is

What purrcat259 said, and I think that the page should explain it, we will add a tooltip.

for some languages CER is more relevant than WER. Thai and Mandarin have no word boundaries, so we score them by character, and Japanese gets a reading-based CER.