The text output for the __() function works for button text, but not for the aria-label and title attributes.
This setting:
produces the following output:
<a id="brxe-kecugz" class="brxe-button bricks-button bricks-background-primary" href="https:/..." title="{echo:__('Discover all products','lang')}" aria-label="{echo:__('Discover all products','lang')}">
Entdecke alle Produkte
</a>
This doesn’t happen just with this custom language domain but also with the default ones from WordPress or Woocommerce.
For example, try using:
{echo:__('User Nickname')}
or
{echo:__('Welcome to the store','woocommerce')}