> those not directly exported with `goog.exportProperty` will also not be exportable

It is not clear to me what you are trying to say here.

The truth is that where we have `goog.exportProperty` calls in the source, properties are unconditionally exported (independent of any `@todo api` annotation).  The presence of a `@todo api` annotation in this case means that these exported properties will also be documented (this is a good thing).