The first is correct. The second is questionable. Please forgive me for a long-winded explanation.
Neither A nor B = Not A and Not B = “None of A and B”. “French or German” is a noun phrase; call it C. So we have “None of A and B” spoke C. Not one spoke French; not one spoke German. This is what you want to say. Your first version is therefore correct.
“Nor” commonly follows “neither”, but not across a verb as in your second version, which uses it to connect Frank and Germaine in the subject, and then attempts to connect them with languages in the object. It may be used (sometimes stylistically) if there is a preceding reference. For example: “We called. All was still. Nor any answer came.“ Neither of these cases fits your second version, which is best regarded as questionable, or even wrong. If you replace the last nor by or, it is correct because the subject (Neither F nor G) and object (French or German) become clear.