For editing beancount files there is an Emacs minor mode available. I find it useful and a quicker interface to use than Fava (which is already great).

I did feel that the most important command is not fast enough to reach (beancount-insert-account; bound to C-c '). The following command can be used in your init or .spacemacs to bind the insertion of accounts to C-c C-c as well:

(eval-after-load 'beancount '(define-key beancount-mode-map (kbd "C-c C-c") 'beancount-insert-account))