Apologies in advance for my english). Can someone tell you exactly how wind from speedtree works in UE4? Firstly, the best plus parameter must be set in the material node, otherwise the animation will not play at all. Secondly, it is very different from the animation in the speedtree. And it differs for the worse. How can this be fixed? Or could it be easier to do the animation in some other program? Thank you in advance
Set up wind in the UE4 or Games versions of the SpeedTree Modeler, and then use export to game to make the .st file to import into UE4. The importer will set all the correct info into the materials for you.
Here are some relevant docs pages to cover each of those steps. Hope this helps