Hello there!
Datasmith works well for importing entire scenes directly into Unreal. However, as you mentioned, it struggles with converting complex V-Ray materials to Unreal’s PBR material system, especially when using UVs outside the 1:1 space.
So if you are working with Datasmith you will probably need to cleanup the entire material network, which can be time-consuming.
You can use V-ray to Unreal Plugin that can help you bridge V-ray scenes from 3ds max into Unreal.
This will help you keep your V-ray materials intact and work in Unreal.
Downside of this is that it can be limited in terms of interaction with the unreal ecosystem, and may not be performant.
Here are some tutorials by Chaos on importing V-ray scenes to unreal, hope it helps!