In general there's a XML file (latest version here) that needs to be translated.
https://github.com/vitorpamplona/amethyst/blob/main/app/src/main/res/values/strings.xml
We already support some languages, e.g. Arabic
https://github.com/vitorpamplona/amethyst/blob/main/app/src/main/res/values-ar/strings.xml
From time to time, new variables get introduced that then need additional translations or they will show in english.
If you know git, you can send a PR, or just send the xml file to Vitor or me and we will add it.