Is community theater important?

I highly doubt that. You have done very many theater productions, so you have A LOT of experience in this field. If you still feel skeptical, you can ask one of the directors or producers to write a recommendation letter so that you have a solid foundation for college because you will probably need a letter of recommendation, so this is a good opportunity for you!

I agree with @lapoozle, I think you're fine. I'm curious if you plan on applying to an acting or theater program? Or are you just curious how a school will look at this EC in general? Personally, regardless if you're applying to a theater program or not, I don't think schools will look down on you.

Unless your high school has a particularly robust theater program I honestly think your community theater involvement will actually look better for you. However, I only think that because I'm assuming your community theater functions at a higher level than whatever your high school is offering. It's possible if you're applying for a theater program that some colleges might find it a bit odd you weren't involved in your high school club but as long as you can properly sum up your involvement on your application you should be fine.

Generally, colleges are usually going to assess extracurriculars by the level of involvement they require—how much time was committed, how much initiative did you need to take to get/stay involved, what level are you involved at, and what leadership or responsibilities did you end up with. If I was to guess, and this is knowing nothing about your school or community theater group, community theater probably requires more time and initiative to remain involved than a drama club, probably functions at the same or a higher level, and might just be a bit less remarkable from a leadership perspective (depending on what position you hold).

I think if you're looking to get into a theater program than @lapoozle's suggestion of getting a letter of recommendation from someone high-up in the community theater group is a good idea. Good luck with everything!

I think you've done enough in the field of public theater.