The first line of the project config file generated when using the command, tmuxinator new foo --local contains a path to the global tmuxinator config directory. e.g. ~/.tmuxinator/foo.yml, instead of /some/directory/.tmuxinator.yml.
I'm unaware of any problems this causes, but it's probably a bit confusing to the end user.
(It's also confusing that the local project requires a name that isn't ever used anywhere, but that's part of a larger conversation...)