Japanese is a special case, because most of the Japanese sentences come from the Tanaks corpus, which... consists of sentences written by learners of either Eng

Japanese is a special case, because most of the Japanese sentences come from the Tanaks corpus, which... consists of sentences written by learners of either English or Japanese who likely weren't all that qualified for the task. However, the content is actively getting curated. E.g. https://tatoeba.org/eng/sentences/show/137571 https://tatoeba.org/eng/sentences/show/137571 is a translation of "I love you." owned by a native speaker. The search form doesn't make it easy to find native-speaker translations, though. The search option to limit results to native-speaker sentences only works if you're searching in the target language. E.g. if you want usage examples for "愛": https://tatoeba.org/eng/sentences/search?query=%E6%84%9B&from=jpn&to=und&user=&orphans=no&unapproved=no&has_audio=&tags=&list=&native=yes&trans_filter=limit&trans_to=und&trans_link=&trans_user=&trans_orphan=&trans_unapproved=&trans_has_audio=&sort=words&sort_reverse= https://tatoeba.org/eng/sentences/search?query=%E6%84%9B&fro... If you're only using Tatoeba as a data source for automatic creation of course material, though, you can filter using whatever criteria you want.