For Untrustworthy, the people and the scene were both so utterly unfamiliar that I needed more familiar touchstones. This meant adding a central river which characters had to cross using bridges. It also meant creating a new form of going, the transportation sleigh. A reader even asked me if Caboss is a snowy world. And I'm still not sure! But all these alien things have familiarity baked right in. We all know what sleighs and bridges are. This made it easier for a reader to connect to what went on in that book.
No matter how bad your review is, it will still be listed on your reviewer page on Amazon (yes, they exist; just click on a reviewer's name). This is a small spreading of news/linking back, and it will be helpful—almost no matter what you say. Almost.
Because this is not a negative review, you can add some length to it. But because it's not unremittingly positive, it does not have to be lengthy. The ideal length is probably about 50 to 100 words. If you want to say more, contact the writer in private. For self-published works, editing and republishing are usually pretty easy. Hence if you find a glaring translation error, the writer can fix it. You can save the day with your review.
Yes, a publisher will edit your work. But if your work is impossible to read, due to typos, improper punctuation, spelling errors, etc., then it's highly likely the person(s) who passes along manuscripts from the slush pile for further consideration will just toss yours into the circular file.