This is great! It sounds like you have a group of young people who are changemakers in their community. The Leadership resource that you are using is a great one to use to develop their skills even further.
I believe your question is looking to link up with other youth organizers in California, is that correct? I would encourage you to check out the California Endowment, which has programming for youth activists in your state. Depending on the age range, I am also familiar with Afterschool All Stars and LAs Best as great out of school time opportunities that focus on leadership development. I'd also point you to the Funders Collaborative for Youth Organizing as a very helpful resource in this work. Finally, if you are looking for more resources for team building and other activities to support youth, selpractices.org is also a great resource.
Being an ally to youth leaders is important work! Thank you for your efforts and for your engagement. Wishing you the best!