You're both right that it could mean "Starting today I will go to the mountain every day." You should use the flag to report this. I think maybe the reason they translated it that way is there's no specific subject which leaves a little bit of vauge-ness. But I think you should definitely report it, my Korean boyfriend says he doesn't think it's a command. Idk -O-
Classic Korean informal speech. Korean speakers often drop the subject/object of the sentence. It's assumed to be implicit. If we had context we would understand what's going to the mountain. But we don't have any context so we should understand that it's grammatically acceptable to drop the subject.