It's very complicated to build a good translator, it's not only that you need a rich diccionary for every language, also the rules, sintaxis and ortography of each of them. Because of this it needs many years of development. That is the reason because a lot of FOSS projects they just threw in the towel or they use Google or Bing APIs, and that only acceptable translators are found among proprietary apps, even paid ones (Deepl, which in it's free version is pretty limitated in vocabulary)