Not too sure, but perhaps the FiveAgonLibs is using the Geomerative library internally, so Processing doesn't know which one to pick (particularly if they are not at the same version).
If that's the case, two solutions:
- Remove Geomerative, as you can use the version shipped with the other lib.
- Search in the FiveAgonLibs the Geomerative jar (if it is separated) and remove it. I suppose Processing will then pick up the installed Geomerative (hoping it is compatible).