3d cursor + custom orientation

i describe sequence of my action and devs - this work as it should?
1-simple sphere
2-align 3dcursor to random face of sphere (orientation - gepmetry)
3-set transform orientation to - cursor

and this is question: when i push + in orientation panel - blender don’t take orientation of cursor as a custom orientation…why?

The orientation is taken from the object and not the cursor.

You can define custom transform orientations, using object or mesh elements. Custom transform orientations defined from objects use the Local orientation of the object whereas those defined from selected mesh elements (vertices, edges, faces) use the Normal orientation of the selection.

https://docs.blender.org/manual/en/2.79/editors/3dview/object/editing/transform/control/orientations.html

Just select the desired face and create a new orientation.

but if face now not in state from which aligned cursor.

i think cutom orientation must take curent orientation of gizmo whiout attach to object or components. user can place some how in custom place 3d cursor and want to add this orientation “as a bookmark” custom orientation - but…can’t

Orientation of 3Dcursor is a new feature. Not every aspect of Blender have been updated to take it under account.
In a previous release, custom transform orientation was updated to use view point by enabling a checkbox.
There is no way to align view to 3D Cursor orientation, although view can be centered to 3D Cursor, for example.
But those kind of things will probably be added in future releases.

Actually, you can add an empty object aligned to 3D Cursor orientation and align view or create a custom orientation from this empty.