I applied for the event , After the result is it possible to modify the cosplays list i announced during registration . If yes how can i do that?

This is a "probably will take" cosplay list. It's not definitive and it's only up to you, what cosplays you will take with you. But bear in mind, that if you will take the exact same cosplays next year like you had this year (if you were at the previous edition of the event) then your chances to get accepted next next year will be less likely.