OK I'm going to be a total spoilsport and kill off the speculation that these recordings could ever be Rudolf Steiner the Austrian philosopher.
Rudolf Steiner or more correctly Rodolphe Steiner was a bass who participated in the the festival of French and Spanish Trade Unions held at the Trocadero in Paris on the 6th June 1931. This had a musical element that included:-
'Une belle partie artistique complétera cette manifestation, avec le concours de l’orchestre symphonique, sous la direction de M. André Cadou; de Mlle Marie-Louise Oger, violoniste virtuose, 1er prix d’excellence international ; M. Edinger, pianiste, 1er prix du Conservatoire ; M. Carloff, de l'Apollo, baryton ; Mlle Wilhelmine Coudray, de la Sootété des Concerts du Conservatoire ; M. Rodolphe Steiner, basse chantante, ainsi que d’autres artistes de valeur.'
It would seem then M. Steiner made some impression and was whisked away to make a few recordings at the Pathé studio. they may of course be terrible and the records were then quietly/quickly withdrawn due to minimal sales.
It would be interesting to delve into the musical elements of celebrations by socialist-communist-unionist supporter both in France and Spain when the Second Spanish Republic was established in April 19,1 and whether it has any bearing on the lieder Steiner recorded, or indeed if the other musicians were supporters for the cause or just paid to entertain.
I still have zero idea who Steiner is - or even if his name is Rudolf, Rudolphe or Rudolpho as he could be German, French or even Spanish for all I know.