I'm trying to translate two strings called Forgot password and Create Account on Login Page and Forgot Passwords Page. Although the strings have been translated it appears only in Greek (Greek - English Site)
The said plugin "UsersWP" isn't on our compatibility list (https://wpml.org/plugin/). But since you've mentioned that you can see the strings in WPML and translate accordingly, while these still show in Greek on frontend. I believe you may need to contact plugin author to check for this. Perhaps it needs to take care of localization for frontend too.
Theme and plugin authors are welcome to join WPML’s Go Global program, which helps them make their code multilingual ready. Together with WPML’s compatibility team, they can test and confirm that their theme or plugin works with WPML. See https://wpml.org/documentation/support/go-global-program/ for details and you can refer your theme/plugin provider to this as well.
However, you can also check this beforehand by switching to another theme and with WPML plugins only, to ensure if it works. In this case, you can activate other plugins one by one to find out any conflict (causing it not to work on frontend).
IMPORTANT: Take full backup of your website and database beforehand. It is highly advised to try the above mentioned on a staging/dev site first, so your live website isn't compromised.
