My AnHeuermann/JuliaFMI was a first try on getting a FMU simulator to run with just Julia. I started the project to teach myself Julia and did most of it during my free time. As I don’t have much time to actually finish the simulator and stumbled across some fundamental difficulties, the current state is not satisfying.
@ThummeTo and I are in contact and I will probably archive the AnHeuermann/JuliaFMI repo soon. The fmi.jl project is actively developed, so it has the potential to become the default FMI tool for Julia based FMU import.
I guess FMU export on the other side would be best implemented in the available packages that deal with ODE/DAE simulation. According to this issue about FMI support it looks like ModelingToolkit.jl will add something in that direction.