Version 2.0 of the GrassENGINE4 is available for download from the BE courses drive:
Have another look at the readme ... you now need to press T every time you'd like to update the mesh.
This version is much more robust that the last, but I did find it was a little sensitive to setting up the port in the grasshopper script. With some perseverance you'll be fine. Once I had the port set in the grasshopper script matching with the port that UE4 is looking for I couldn't get it to crash unless I went over the poly limit; which is 8000.
I initially thought 8000 as a poly limit was a problem, but upon reflection I think its a reasonable "real world" number of components for a project this size. Interested to hear you comments below if you have an opinion on this.