[2022] Baking details in editor is infuriating.

What you've described is not the default behavior for baking foliage (neither in the legacy editor, nor in the Devkit).

For the legacy editor, details will bake on the materials that you've manually configured them to bake on. You can configure these things directly from within the legacy editor. Although it sounds like you're using the autumn leafy materials from the Russia map—which aren't normally available to the legacy editor. Are you using the Devkit?

Materials and foliages are configured within individual asset files. These cannot be configured within the Devkit itself. Instead, you'd need to create and configure these from outside the game, using the vanilla materials/foliage as a reference point.

The relative path would be ...\Steam\steamapps\common\Unturned\Bundles\Assets\Landscapes.

But the vanilla configuration of these assets would not cause the issue you're describing. By default, the Russia_Leaves_00_Material.asset uses foliage from the Russia_Leaves_00_Collection.asset. From top to bottom in the file hierarchy, that collection consists of Russia_Leaves_00_Foliage.asset (orange grass), Pebble_00_Foliage.asset (pebbles), and Russia_Leaves_01_Foliage.asset (orange grass).

EDIT: If you are using the legacy editor, then you just need to scroll down to the bottom of the materials menu/list to configure your selected material. Alternatively, scroll down to the bottom of the foliage menu/list to configure your selected foliage. Specifically, you'll want to change what groups your foliage details are part of, and then make sure that your material has those groups enabled to bake on it.