Sentry HA is supported as of CM / CDH 5.13.0
To enable Sentry HA via the API, after meeting the prerequisites, you will need to:
1) Add an extra Sentry Server role to a host
2) You may need to go to the Hive service and Enable Stored Notifications in Database (HMS group setting)
3) Generally follow the public doc instructions for enabling Sentry HA with rolling restart, but using API commands instead of GUI actions.