I just watched GDCs video of Far Cry 5’s terrain and how Ubisoft managed to make it.
It has a lot of awesome tools, tools that would make the Proceduarl Foliage tool a lot better!
check it out here; Procedural World Generation of Far Cry 5 - YouTube
What I like the most is how they use biomes;
Different kinds of foliage in for cravices/rivers (flowmaps).
Change foliage size on height/altitude.
Face foliage towards slope.
Different sizes of foliage in and around thick forests.
The tool we have now, is pretty basic but does the trick for quick and dirty work.
But by adding the factors described above here, you could make your foliage more nature based so to say.