You might want to try learning to do it yourself. Translation is one of the best entry points into programming. And Mlem is open source.
Step one: learn a little about git.
Step two: grab a copy here: https://github.com/mlemgroup/mlem
Step three: pour through the text files and figure out how they implemented translation.
Step four: start translating!
Step five: send a pull request to the maintainer, so they can merge your changes in.