Instead of doing that, you should look into applying the foliage blocking volume type onto a geometry asset that can be edited in engine.
Not that properly responding to an alpha map wouldn’t be useful mind you - in fact, if you went and did that and allowed for things to say grow based on the alpha value, you’d be able to easily resimulate roads with paths and animal tracks where the grass won’t grow as tall near them.
Both systems have their uses. Merging the 2 would be ideal. Using vertex paint on the mesh so you can define growth/whatever else in editor before resimulating.