So, while looking around, I found one of the best comics translated, but I always thought this whole comic was posted on E621. Since it isn't uploaded, can I just upload them all and that's it? I don't know if this comic is currently behind a paywall, so I want to know as soon as possible!

If the untranslated version is up its safe to post. Otherwise do some research on whether its commercial content and if so. Check if its at least 2 years old.