it's about timing the translation. Magento had the same Problem in the Checkout or the Catalog in early Versions.
Here is an example: In an old Version, the Add to Cart Button was not translated anymore after adding the product to cart. The old Version had the translation in the initialization function:
while the new version has the translation in the handler function
The solution is, to translate the text as late as possible. For example, instead of being translated the Initialization function, it could be translated in a
getText() function which is bound to the HTML element.
You should also take a look at the file
pub/static/frontend/Your/Theme/<language>/js-translation.json (or something similar)