Last week I introduced you to non-professional translators. They have never received an education as translator and therefore do not have any certificate whatsoever to prove their qualifications.
The problem is that “translator” is not a protected job title. everybody who speaks multiple languages, could just call himself a translator. Of course, there is more to it than just speaking some languages. There is grammar to perfect, lots and lots of terminology and translation techniques to be learned, special knowledge in a working field to be obtained (e.g., apps and video games). Furthermore, a very good understanding of cultural differences is absolutely necessary. People are studying this for several years for a reason.
When searching for a suitable translator, I highly recommend you to ignore translators without actual degrees and start searching for state-certified translators, graduate translators, translators (BA) etc. – so basically any actual job title indicating their qualifications.