It depends where they store their content. If their text lives in the theme, or Metafields, Translate & Adapt can translate it. If not, we can’t but other apps can, in the front end. Here are apps that do it with links to the relevant feature:
The checkout should follow the language of the store. If it doesn’t, it’s almost always a 3P app causing it that doesn’t use the ‘routes object’. Try turning off all apps and seeing if the correct language persists, and if so turning apps on one by one until you find the culprit and speak to their developers.
You definitely shouldn’t need a different store for each language.
Hi @alljoe , was there a part of the answer I gave previously that you’d like explained more? Apps that don’t save content natively to Shopify’s Translations API / database are not visible to Shopify, and thus not translatable by Translate & Adapt. The reason other apps can do this is they are able to also translate in the front end (they find and replace the HTML). To solve your problem you will need to build your content differently or use a 3rd party translation app. Some of those that work with the Translations API (so work with Translate & Adapt) and also have this capability are listed in my previous post.