How do i change the button text "subscribe", from the "simplenews" module, in drupal 8?
I figured it out due to 4k4's comment

Basically you can translate it english-to-english under /admin/config/people/simplenews/settings/subscriber/fields/
It's a part of the configuration translation module.

If you get the error message "The configuration objects have different language codes so they cannot be translated:" look at this thread for the solution for that: How to change default language for configuration entities