Makes sense. Small languages are usually written by people who speaks them, so bad grammar hints lack of effort or automatic translation. IAs usually are not a factor; they don't support them or spammers prefer to target more widely used languages.
For English, bad grammar hints a non-native speaker who made a great deal of effort to write in a language they don't fully grasp, about something they really care about. IAs usually get the grammar better than people. So, trustworthy.