Hidden hotkeys in the 2.8 I can not find many hotkeys in the "Keymap", but they are searchable. I need find where they are, because I want to add more variants. 

Is it bug or it is hidden somewhere?

For example "Time scub" or "Gizmo":
The gizmo category is not included in the keymap_hierarchy.py which can be found in release\scripts\modules\bl_keymap_utils. Therefore the category isn't displayed in the overview of the keymap. When you export the keymap you can view all shortcuts and it includes the ones for the gizmos.
It's not entirely clear to me why these entries are missing, hence I've created ticket T77799 on Blender's bug tracker. The reply by the UI team will be your definitive answer.