Buddhist scriptures are the views of the Buddha.
Dharma is a precept formulated by Buddha.
Theory is the exposition of Buddhism by Buddhist disciples.
The two parts, Classic and Law, were translated because they were all said by Buddha.
As for the theory, the specific situation is different. There are works by Indian monk Dade and translations, such as The Great Wisdom by Dragon Tree Bodhisattva.
There are also works by China's eminent monk and great virtue, such as Master Hui Yuan's On Shaman's Disrespect for the King.