I just tested DeepL machine translation for the first time in probably a year by plugging in random toots from Japanese friends on here. What I found was that it made numerous mistakes, but it manages to make the English sound natural, so someone who doesn't actually read Japanese could be fooled into thinking the translation is accurate. I used to be kind of rooting for DeepL, but these days #IHateAI so much that I can't root for any of them.