Hello,
May I ask how you obtained the accordion and if you have any idea of the age?
A. Steiner Harmonika Erxeuger Tobaj is German for A. Steiner accordion producers Tobaj. Tobaj is a town in the district of Gussing in the Austrian state of Burgenland.
The only reference I could find pertaining to A. Steiner and Harmonika was in the following Wikipedia link (German):
https://de.wikipedia.org/wiki/Steirische_Harmonika#Albin_FlatscherThe site provides a good history of accordions and the manufacturers, BUT yours is listed under: Other harmonica builders whose companies no longer exist and of which no further data are available (as shown below).
Weitere Harmonikabauer, deren Firmen nicht mehr weiterbestehen und von denen keine weiteren Daten vorhanden sind.
Karl Frey, Amstetten Niederösterreich
Gottfried Kurnig, Deutschlandsberg Steiermark
Hans Polz, Schwertberg Oberösterreich
S. Gert, Voitsberg Steiermark
August Damm Eibiswald Steiermark
A. Steiner Tobaj Burgenland
Josef Hahslacher Möllbrücke Kärnten
Obviously, that is not what you want to hear. So who is A. Steiner? If you knew the approximate age and wanted to take things further, you could search on Ancestry.com or another site since you know A. Steiner is from Tobaj Burgenland Austria. Or there are sites specifically with accordions in mind such as,
http://accordions.com/. Perhaps, you would obtain more age/date related specifics from someone who has knowledge of accordions.