Library loading using bpy.data.temp_data()

Does anyone understand how to properly use bpy.data.temp_data() to create temporary data for loading libraries?

API reference: https://docs.blender.org/api/current/bpy.types.BlendData.html#bpy.types.BlendData.temp_data

Diff: https://developer.blender.org/rB9e0921497912cbfe9846358d1cb1220f88315f80