Why are you not using the builtin asdf-output-translations facility? Instead, you're interfering with it. This smells like code from before 2012, to work with ASDF 1. You should remove that defmethod output-files :around method and anything related to it.
Shinmera's portacle looks like a better modern alternative to the old lispbox. https://shinmera.github.io/portacle/ (Warning: I haven't used it.)
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org A tautology is a thing which is tautological.