It seems that the RasterExtensCoercer removes every attribute which name is prefixed with underscore, if you set Raster Extent or Data MBR Extents to the Extents Type parameter.
See the attachment. (FME 2020.0.1)
This post is closed to further activity.
It may be an old question, an answered question, an implemented idea, or a notification-only post.
Please check post dates before relying on any information in a question or answer.
For follow-up or related questions, please post a new question or idea.
If there is a genuine update to be made, please contact us and request that the post is reopened.