Rodenstock added the "APO" designation to their own Sironar N lenses without changing the design/manufacture of the lens, so having the APO designation on the lens is just marketing and not an indication of optical properties.
I've owned both Rodenstock APO Sironar-S and Sinaron SE lenses, and they were identical (despite the lack of the APO designation on the Sinar lens). Similarly the Sinaron S lens and APO Sironar N lenses are identical.
You won't find the APO designation printed on Sinar branded lenses, they chose not to adopt Rodenstock's naming convention on the Sinaron line. However, they are all just as "APO" as the Rodenstock lenses labeled with the APO designation.