Loading a collection with objects using bpy.data.libraries.load, to avoid using a bpy.ops operator

I want to append a collection and the objects within that collection from a blender file, using bpy.data.libraries.load. The reason to use bpy.data.libraries.load is to avoid using a bpy.ops operator, which will make the python script slow. If I load a collection from the blender file using the code below, the collection remains empty.

MainDir = bpy.path.abspath("//")
filename='Plants/Forbs collection.blend'    
    
with bpy.data.libraries.load(MainDir + filename) as (data_from, data_to):
    data_to.collections = [c for c in data_from.collections if c=="Woodland forbs"]

for new_coll in data_to.collections:
    instance = bpy.data.objects.new(new_coll.name, None)
    instance.instance_type = 'COLLECTION'
    instance.instance_collection = new_coll
    bpy.context.scene.collection.objects.link(instance)

Does anyone have a suggestion?