Inform users that have not tried Content Translation yet, that they can enable the beta feature. There are several kinds of events that the information can be attached to in order to make it relevant (we should make sure that we don't inform about the existence of the feature more than once for each user, even if several mechanisms are supported).
This is one of the experiments defined as part of T90532: Ask users to try the beta feature (tracking) to invite users to try the beta feature when they are creating a new page.