Yeah, don't blame yourself. Vue's terrain handling isn't as good as even the first Terragen's ones...many use things like WorldMachine and GeoControl to create superior terrains for Vue...I would too if I can afford those programs
I tried the 30 day trial of GC once, but I stupidly hardly used it and waste dmost of that time Worldmachine looks too complicated in comparison, it seems too filter-node reliant