MostHost_LA is right you should only use the Anim BP for getters not setters, use it to drive your animations states.
But you will still need to cast to your character class, and for these custom variables have you set them to private? as you wont be able to access them if you have.
Example below of how you should cast to your character.
https://gyazo.com/87c67d0d8232294bfd0afe48f45255b0