Editora 0.9.10. Archived, so links from that release keep working. Read the 0.17.0 page →
Appearance: Set UI Language…
appearance.setUiLanguage Choose the interface language (applies after restarting Editora).
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Appearance: Set UI Language…, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.