I am not sure if this is what you are looking for and there may be another way. For me when I wanted to dynamically change the values of a gerstner wave I had to call a c++ function called recompute waves. Here is an example blueprint for changing the properties. UE Change built in water gerstner wave property posted by delebash | blueprintUE | PasteBin For Unreal Engine. You can see I am overriding some properties but in order for those changes to take effect I have to call a custom bp function called Recalc Wave. This BP function just exposes the c++ function GerstnerWaterWaves->RecomputeWaves(true); You can see my custom function here WaterBlueprintFunctionLibrary/Source/WaterBlueprintFunctionLibrary/Private/WaterBlueprintFunctionLibraryBPLibrary.cpp at main · delebash/WaterBlueprintFunctionLibrary (github.com). This is part of my Global Environmental System for UE here delebash/UE_GlobalEnvironmentalSystem: Make your landscape interact with weather, wind,water,foliage and your player like the real world. (github.com) hope that helps.
Also, you may want to consider the marketplace asset Oceanology as it is very good and much easier to control via BP. Oceanology 6 will be coming out soon with a new FFT system and significant enhancements, but OC 5 is still very good if you want it now. UE water is still experimental since UE 4.6, and I haven’t seen anything about it getting any love or attention. There have been some bug fixes, but I haven’t heard anything about enhancements or moving it to production. Another good asset is Fluid Flux but it is pretty expensive