For best results there typically should be LOD models created. This does not necessarily mean less triangle count or using LOD textures (which are often created automatically from full textures anyways), but also applies to adjusting UV coordinates, convert ordered nodes, changing shader settings and removing collision, dynamic parts, particles etc.
There are some worldspaces (also from mods) that may use a lot of dynamic LOD models, so it is necessary to have dedicated dynamic LOD models without particles or ordered nodes, otherwise visuals and especially performance will be affected severely. Decals often cause visual problems since they are always painted in front of other shapes etc.
In case of some waterfalls, it is also necessary to create a static LOD model in addition to the dynamic LOD model. A mod containing dynamic LOD models that are the same as the full models for waterfalls, are a hint that the intricacies and specific details of dynamic LOD and object LOD generation are not understood. Without properly created dynamic LOD models and rules there can be visual and performance issues.
Use the official DynDOLOD support forum for qualified help and advice in case of questions how to create proper static object LOD and dynamic LOD models. The processes and features continuously evolve and change, do not hesitate to ask.