LocalAIz

There are many models you can choose from and they seem to change week by week. The larger the parameter size the better. In my testing, Gemma3 27B via Ollama has been pretty good.
It's recommended to use Ollama instead of the in-app models. Try a few different models to see what works best for you. Try it on some of the more difficult strings with placeholders or special formatting.

First open your app source directory (where your .xcproject file is). Then click on the 3 ellipsis next to your app name. From there you can toggle on or off any languages you want to have in your app.
For any localization languages not listed in the app, you can add localizations in Xcode under the Project Info screen.

In Xcode navigate to your strings file then right click on the string you want to skip localization. Then choose 'Mark as "Don't Translate"'. After this open your app project in LocalAIz again.