Nochmal: Die wörtliche Übersetzung passt hier m.E. nicht so gut.

der Form halber

maxxpf: note that perfunctory (adj.) / perfunctorily (adv.) implies a certain lack of care. It's therefore not appropriate in this case (operating manuals) imho.

#3- You must be right, at least if it is really still done carefully. And I think your translation will work even if it is only done perfunctorily. :-) Which is not totally unlikely since I do know -from experience- about things we do at school that are done for form's sake only and perfunctorily. :-)
I basically just didn't like the direct translation and would even say that in German the expression "l'art pour l'art" is totally out of place. In German it would, in my opinion, certainly be better to say "nur der Form halber" as well, or: "Es war nur noch eine reine Formalität."