There are many telltale signs of (unedited) machine translations, restaurant names in this case being a very obvious one that even people who aren’t native speakers of the target language can recognize, and there are many less obvious ones that usually will tell a translator who is a native speaker of the target language that a text is an (unedited) machine translation.
Maybe it’s an idea to find a reliable proofreader of the target language and ask them what they’d take to highlight such signs and explain in comments why it means the translation is just an automatic (unedited) Google translation, depending on what amounts you paid for the translations, it might be worth it, as an additional proof, but, of course, I don’t know if Fiverr would accept that.
Another alternative would be to invest a bit more into a proofreader and have them go over the translations to make them usable. I’d not order a proofreading gig directly though but ask the seller to check one of the files first, so they can tell you if a “quick proofreading/correcting job” is enough, or if they basically would have to rewrite every sentence, in which case it might be better and not even more expensive to have the texts translated again from scratch.
“Translations” like that are one of the reasons I don’t even offer proofreading gigs myself because, among other things, you’ll get people who want you to “just” proofread translations without the original text, which, in cases like this, when even restaurant names have been translated, often will leave you scratching your head, and even if the customer knows that an actual proofreading should be done against the original text, many don’t want to pay much for proofreading while it can take one just as much (or even more!) time to correct translations than to translate from scratch, depending how bad it is.
Not all machine translations are bad, though, it depends a lot on the language in question and the kind of texts - but you really can’t use completely unchecked and unedited machine translations at all because it’s simply too risky, even if there aren’t many errors, it can be bad errors, like the restaurant names (another great example being the infamous “Turkey” translation - the animal instead of the country in a list of countries, an error you’d think even a bot shouldn’t have made).
Some kinds of mistakes can happen due to typos, careless mistakes or tiredness, of course, but translators who are native speakers usually can see if things are mistakes made by a human or if the text has just been machine translated as a whole and not been corrected/edited, there are also signs/hints that are less obvious to someone who doesn’t speak the language, or which they can’t recognize at all, of course.
Well, hope it will be dealt with in a fair way, and that you’ll find a reliable translator. They exist, you just need to find them (and be willing to pay for the time a manual translation takes and plan well enough - if someone asks for a humanly impossible delivery time and the seller has no problem with that, chances are he or she will deliver translations).
I know you’d like those translations refunded, of course (and in that case, you could use the refund against proofreading or new translations), just some thoughts that might be helpful.