So I am fairly new to UE4 and having issues with foliage

Currently running 4.14.3 on UE and every time I added even just two or three bigger clumps of grass on my map I got an error message regarding the meshes, I messed with numerous settings and that message went away (not sure how tbh) either way now im still experiencing issues with the LOD “instances meshed dont yet support unique static lighting for each LOD, Lighting on LOD+1 may be incorrect”. I thought I played around with the LOD settings on my skylight and still cant shake the error message. If I could get some help with making some grass and trees thats not to taxing on systems. Its not going to be for a showcase, this is for my actual game im making for VR. Its only one map and its kind of big and needs to be populated kinda heavily with trees and grass. I have grass painted on the landscape itself and that looks fine but id really like to have some grass sticking out for players to see. Am I better off with just keeping the painted grass? First pic is the grass im using and I tried playing with the density and other settings in the modifiers section, the second is the where the entire game will take place in (showing for size, might go down a tad but its gonna be a moba so I need the space) and roughly a third of that needs to be filled with trees not to mention the buildings and other objects. Again I tried different methods and im just here to see what you guys would recommend. Doesnt need to be high def but not borderlands cartoon quality and at this point as im just trying to get the concept of the game out and beautifying can come later. Aside from the grass any tips to get more objects in a map at the lowest cost will be greatly welcomed and appreciated. I tried youtube videos and forums and couldnt really find what I was looking for which is why im here now, please dont say im lazy cause I looked for the last two days on countless forums and youtube videos for any help and nothing was really close to what I was looking for. Thanks in advanced!

hey, i am working on a similar project and have experienced the same problem. the unreal developers have a youtube channel that has an environment training video Unreal Engine - YouTube