Judging from the pictures of the OP consisting multiple split extrusions, looks like the new “Elmo” (RebuildCrv) tool for a minimalistic rebuilding could help with making the input geometry far more clean, thus easier to apply fillets. Perhaps it would be a matter of minuted to rebuild these and try again with the fillets.
One more thing to mention. It’s often repeated in many topics. Asking for help works best if there is a sample 3dm file or at least some more details, such like what’s the size of the model and the radius to be applied. This particular eagle model could accept tiny fillets even in this state of the geometry. However, Rhino and most CAD programs will struggle with larger fillets due to the split extruded faces and the fact that some of the pieces are really slim and end into a sharp edge.