Something you can do is implement models from the literature, there’s a bunch here but you can probably find something missing (you need to be a bit acquainted with the domain though):
You also have stuff like this:
If that’s really useful (need to be tested) then it could be added to the libraries.
For optimization I think BlackBoxOptim doesn’t have a generic interface, there’s no good CMA-ES implementation (I’ve got one that works but it’s not as good as Python’s), and there’s probably plenty of little things one can do, but you need to be well informed about the packages (which comes by using them mainly, and reading the issues/PR).