Sorry, I mistook approach. My syntax checker is specific to my use case. It seems that the syntax checker needs to run by not cucumber command but rake task like feature-mode.el. See  https://github.com/michaelklishin/cucumber.el/blob/0d29e4a2921146eef8641e488a272d3b9e8f8680/feature-mode.el#L86.

I'm not sure that it can make the general cucumber syntax checker. Do you mind if I close this PR?