https://gpt4all.io/index.html not appimage but run on Ubuntu: https://gpt4all.io/installers/gpt4all-installer-linux.run

My opinion is the best translation program:

1. Firefox Translations provides automated translation of web content. Unlike cloud-based alternatives, translation is done locally, on the client-side, so that the text being translated does not leave your machine. Firefox Translations was developed with The Bergamot Project Consortium. https://addons.mozilla.org/en-US/firefox/addon/firefox-translations/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search

2. Desktop version of Bergamot MT: https://translatelocally.com/ translateLocally is a privacy focussed machine translation application which translates content privately and securely on the user’s own computer.

Not open source but privacy friendly:

Brave Translate (Lingvanex) https://support.brave.com/hc/en-us/articles/8963107404813-How-do-I-use-Brave-Translate-