You are right, it works now. I now understand: in the epilogue code I am in the cl-user package by default, but I have for some reasons to intern any function of my package I want to call.

Unfortunately I cannot adopt this solution because I gives troubles with some dynamically scoped variables I am using in my package code. I have no idea why, but they appear to be unbound now, as they were not dynamically any more, but static.