Greasy Fork is available in English.
Watch for target language element class change, copy new value of textarea to clipboard each time change has been detected.
< Feedback on DeepL - Auto VN Translation Extension Helper
Updated, checked and worked on Firefox and Chrome. If you still have problems please send me a message.
Until 3 or 4 days ago it worked perfectly in Chrome but maybe something was updated in the HTML code and now it doesn't copy the translation.