I found two interesting books that can change some false attitudes towards Mazdayasna/deen zartoshti/Zoroasterism.
Only Gatha (a specific section of the Avesta) is from Zartosht and rest is from zartoshtian clerics.
These perfect Gatha Exposition/translation are Persian/farsi and I recommand Abtin saasaanfar exposition.
*An interesting thing in these two is The great similarity of the teachings and the CONTENTS of these two books with the Qur'an. Maybe it can prove that Zartosht was a Real prophet.
Dr. Aabteen Saasaanfar Exposition of Gatha :
Feerooz Aazargoshasb translation of Gatha: