What would the formal form be (instead of Bála by ses?, the version it corrects to)? Thanks in advance!
Formal (speaking of "vykání") would be "Bála byste se?" for a woman, "Bál byste se?" for a man and "Báli byste se?" for group of more people (from which at least one man).
This is completely fine. I can only think of hypercorrect forms like "Bála by jsi se?" - not correct. You can also say: "Měla bys strach?".
The female form "Měla bys strach" and the male form "Měl bys strach" are currently not accepted yet.
We were also missing all the formal vy forms. I have added them.
“Vy byste se bál” was not accepted. I can’t figure out why. Are the clitics out of order?
As wrote to Praha, I have added the vy forms three days ago. They may not be active for you yet.
Anyway, you really should use the report button if you believe it is correct.