Thank you for the PR. I indeed have some thoughts about this solution:
Currently it would not be possible to dye signs with ALLOW_SIGN_CHEST_OPEN enabled, I think moving the dying logic before the chest open logic would solve that (then players would just need to not have dye in their hands).
Dying is only possible with a right click interaction so the return/cancel logic should also only react to that.
I think defaulting this option to true would be better as there shouldn't be any adverese effect and players expect to be able to dye signs.
You might want to include that one needs 1.14 or higher to dye signs in rhe config comment as that option wont make it so signs get colored on 1.13 and currently the plugin (should) still suupport that.
Fixes #466 and #472. If you need me to make any changes, feel free to tell me!
Hacktoberfest PR