For private questions, you can always e-mail the lead developer of Complementary.
emingyildiz@gmail.com
Discord
For casual questions, suggestions and to get support; you can join the Complementary Discord community.
https://discord.gg/A6faFYt
Patreon
If you want to support the development of Complementary Shaders and get some little benefits, you can become a patron.
https://www.patreon.com/emingt
Github
If you are interested in code, you can take a look and even make pull requests on Github.
https://github.com/ComplementaryDevelopment