How are Buddhist classics passed down? Is it reliable?

Reliable, Buddhist scriptures come from India. In ancient India, Buddhist scriptures were handed down word by word, and the translation of Buddhist scriptures in China has been a grand and prosperous era since ancient times. Most of them were presided over by the emperor, bringing together all the famous literary masters in the country. Every sentence of the translation is finalized after careful consideration and approval, so don't worry about poor writing or insufficient expression. The translation of Buddhist scriptures is very scientific and rigorous.

But I dare not say that there are no Buddhist scriptures invented by later generations, but at least some of the most widely circulated ones are absolutely reliable, such as Heart Sutra, Huayan Sutra, Goblet of Fire, Sakyamuni Sutra, Shurangama Sutra, Diamond Sutra, Amitabha Sutra, Infinite Life Sutra and so on. A Buddhist sutra is enough for a lifetime.