AUPO certification counts for something, albeit, not a whole lot. There are some basic qualifications that AUPO fellowships have to adhere to including access to facilities, faculty and program director duties and minimum standards, research time, access to lectures/grand rounds, journal club etc. While minimal, these basics lay a good groundwork to assure both clinical and academic minimum standards are met. Non AUPO certified fellowships may also adhere to such standards, but less likely. The main issue is that these standards are minimal and sometimes non-specific, and entirely self reported.
In any case, this is kind of off topic. I think there are very good non-AUPO certified fellowships worth exploring.