I mean systems that have to scale to hundred of millions of users and guarantee durability in presence of infrastructure and software failures.

Cadence is used in production by over 100 teams at Uber and multiple outside companies. For example here is a presentation that describes how HashiCorp relies on Cadence for the new version of its Consul product: https://www.hashicorp.com/resources/making-multi-environment.... The Cadence related part starts at 17:30.