Can I draw red when copying Tibetan scriptures?

Yes, Tibetan scriptures are Buddhist scriptures, and there is no time limit for their copying. They can copy it day and night, as long as they are calm and energetic. If you have copied Buddhist scriptures, you should copy them well, and don't tear them up and throw them at will. Doing so is disrespectful to the scriptures and will bring you great karma. Tibetan scriptures can be painted red.