I ran into the same issue and found the following solution to one specific case of your problem. (I am posting it here in case it is useful to someone.) Try including this snippet in your olivetti-mode configuration:
(setq olivetti-style 'fancy olivetti-margin-width 3) (defun custom-olivetti-mode-on-hook () (setq-local flycheck-indication-mode 'left-margin)) (defun custom-olivetti-mode-off-hook () (kill-local-variable 'flycheck-indication-mode)) (add-hook 'olivetti-mode-on-hook 'custom-olivetti-mode-on-hook) (add-hook 'olivetti-mode-off-hook 'custom-olivetti-mode-off-hook) (setq olivetti-style 'fancy olivetti-margin-width 3) (defun custom-olivetti-mode-on-hook () (setq-local flycheck-indication-mode 'left-margin)) (defun custom-olivetti-mode-off-hook () (kill-local-variable 'flycheck-indication-mode)) (add-hook 'olivetti-mode-on-hook 'custom-olivetti-mode-on-hook) (add-hook 'olivetti-mode-off-hook 'custom-olivetti-mode-off-hook) This solves the problem for Flycheck indicators but not for the line continuation indicators in your question.
The bottom buffer below shows the result after enabling olivetti-mode (using the above configuration): 