The problem is that you are using the standard menu search, which only finds operators that are placed in a menu somewhere in blender. To be able to access all operators in this search, turn on “developer extras” in Preferences > Interface > Display > Developer extras.
If you don’t want to turn that on, you can access the operator in the “Imposter Baker” panel in the N-panel.
It looks like the developer has somewhat abandoned the project, however, as the UI for this panel is just one of the inbuilt templates, so most of the buttons there aren’t actually related to the addon.
@Reality_Checker @merch137 @Bracer