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:
https://github.com/magento/magento2/blob/628687b491d2d95e164388bb2f4b97be41a1e211/app/code/Magento/Catalog/view/frontend/web/js/catalog-add-to-cart.js#L23
while the new version has the translation in the handler function
https://github.com/magento/magento2/blob/develop/app/code/Magento/Catalog/view/frontend/web/js/catalog-add-to-cart.js#L121
Since all Javascript resources are loaded asynchronously, it may happen, that your component is loaded before the translation component is initialized.
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)
This File should contain all translations that are used in the theme's Javascript files and should contain your own translation. It gets regenerated if you delete it (at least in developer mode) and is also cached in the local storage of the browser.