Please note that, in general, new plugins and themes to the Catapult codebase are not accepted. The goal is to keep the core Catapult light and include only a consistent set of well maintained plugins and themes that can be expected to be of wide interest.
So, if you need a new plugin or theme, the general suggestion is that you do that in your own repository, maintaining and distributing it yourself. You can add the topic "catapult-plugin" or "catapult-theme" to your repository and users will then find them following links on the Catapult website and README.