There is a demo available. It is regularly updated from the master branch. You can contribute in several ways. If you know how to code or are a designer, you are welcome to contribute using pull requests. If you speak languages other than english, you are welcome to help translate SilverStrike using crowdin. There is a dedicated instance of the demo that can be used to translate inline. You will still need an account at crowdin, but translation should be easier, because of the context.