Custom Error Message

Hello, I am trying to customize the error messages in the login, registration, lost password. However I cant find where to edit or change the text in the plugin files. as you can see in the link I have changed few things but I cant find where to change the rest. My knowledge in HTML code but I can manage however I cant find where you keep the text for the Error messages.

I also have a weird error message when you enter a wrong email address in the lost password. this will also help in translation so please give me the paths of all the related files.

thank you

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