I saw this on an Acer Chromebook (seemingly sold in Japan; it has a Japanese keyboard) and a Samsung Caroline. Changing the device UI to Japanese doesn't seem to help.
 
Chrome Version: 67.0.3396.78 beta
OS: Chrome


What steps will reproduce the problem?

Two options:
(1) In DevTools, print speechSynthesis.getVoices().map(function(x) { return x.name; });

Or
(1) Enable Accessibility -> ChromeVox

What is the expected result?

Japanese appears in the printed output. Or ChromeVox can speak Japanese.

What happens instead?

Japanese doesn't appear.