Thanks for your interested in contributing! The JavaScript Ecosystem wiki page might be a useful resource. It includes a link to (among others) the OMRSJS JIRA project, which we use for issues relating to the generator. There are not many feature requests at the moment though, so I recommend either creating your own, or pinging this topic to try and extract some requests from the community:
The generator is just a Yeoman implementation, so you can learn what you need to know about development here.