All indications are the sentence builder feature is no longer being actively developed or maintained - or supported in new capabilities. Having these features in your app/account seems to be a potential roadblock for new features/capabilities for developer accounts like the version selection.

Workflows are an alternative for customer accounts which have them, but that cuts out many accounts as potential customers for integrations and automations.

Some guidance is needed here on the longterm viability of a certain class of existing and popular apps.