I tried the attribute "unreal_level_path" ,which isn't working.
All instancers were baked into one level.
Is there a proper way to bake foliage instancers into spererate levels?

Make sure you set unreal_split_attr to unreal_level_path

"As an example, using the unreal_material attribute as the unreal_split_attr attribute (unreal_split_attr = "unreal_material") will create an instancer component for each material on the second attribute. If three different materials are used, the instancer will be split to three different instancer components."
https://www.sidefx.com/docs/unreal/_instancing.html [www.sidefx.com]

bobc@sidefx.com
Make sure you set unreal_split_attr to unreal_level_path

"As an example, using the unreal_material attribute as the unreal_split_attr attribute (unreal_split_attr = "unreal_material") will create an instancer component for each material on the second attribute. If three different materials are used, the instancer will be split to three different instancer components."
https://www.sidefx.com/docs/unreal/_instancing.html [www.sidefx.com]

Thanks for your respond, bobc

It sort of worked. Using the unreal_split_attr created same amount of foliage for each sublevel, instead of splitting the instancers.

Here's the attribute values of my setup.