Danville for Asian-American family returning from abroad

Hi All- im an East Bay native, Filipino-American and spouse is native Japanese but English-fluent with a US degree. Both currently working in finance/tech services in Tokyo.  We have 3 kids that are English-Japanese bilingual. Danville attracted us because I noticed the public high school has AP Japanese. I also have family in Walnut Creek. We are thinking of returning home in 1-2 years and seriously considering Danville. The main drivers are to be closer to elderly parents and to earn a higher income, and living in a safe city where kids can roam.  

Would you recommend Danville as far as having a decent sized Japanese demographic? The main concern is wife being able to make friends, finding a good grocery store, and Japanese weekend classes for the kids. We do have family in Walnut Creek, but the slightly better schools and Japanese AP at Danville are draws for us. 

The biggest worry would be being bored. Coming from a large, yet safe, metropolis, the kids are used to having a lot of stimulation. I know downtown Walnut Creek won’t compare, but is that a place teens could go to hangout?

Another worry is kids sports. My kids are into gymnastics, skiing and club soccer. The US Soccer travel-team, pay for play system seems terrible. Tokyo is very competitive for soccer and it’s super cheap for all 3 sports here, so we’ll need to factor sports costs. I assume it will be very easy to do all 3 sports living in the tri-valley area (of course Tahoe is close enough).

Are there any community centers or casual clubs that families like to hang out at? We are members of a very nice swimming/city club here and scared we’ll miss the lifestyle.