Where do Diwali celebrations and garba nights usually happen around Kansas City?

The KCdesi events calendar lists Diwali, Navratri and garba events as organizers post them:
https://www.kcdesi.com/events/

Places of worship and community organizations are listed here. Check their pages for celebration dates:
https://www.kcdesi.com/business-category/places-of-worship/
https://www.kcdesi.com/business-category/kcdesi-community/