Please try to install the plugin to translate the strings: https://wordpress.org/plugins/loco-translate/
Activate the plugin:
1) Go to “Loco Translate > Themes”, click the theme name
2) Click “New language”:
3) Pickup a language, click “Start translating”:
4) Find the word to translate it. Click “Save”:
Ps: In fact, it is not limited to translate things at all, it can be used to replace the strings also.