Questions about the history of heroes.

Most likely not. Because Kujin says in the final cutscene: "No, Gotai. Biara killed Isabel's husband and Frida's father. This is their revenge." Isabel confirms this by saying, "My husband! My country! You will have to answer for much!" The others are either mistaken themselves or pretend not to know.
And Biara has nothing to do but shoot fiery balls from her "cannons." If she had revealed the truth about Railag, she would have done much more harm than with gasoline bombs, and her departure would have been truly magnificent.