1. Which is the main tafsir of the shia – which is said to be the most authentic one.

2. What is the best tafsir for one to refer to within the English language – I’m presuming the list is very limited due to a small quantity of works being translated.

by

1- The main Shia Tafsirs can be divided into two parts: the early tafsirs and modern tafsirs. Among the early tafsirs, you have Tafsir of Qummi, Ayyashi and Majma’ al-Bayan.

Among the best modern tafsirs is Tafsir al-Amthal.

For English I recommend Quran Hadi:

https://www.firstcause.net/quran-english/