Question about A. cacatuoides

Especially with hatchetfish (which stay near the surface), and small tetras such as Red Phantoms or Ember Tetras, I would say yes. The larger tetras (Congos, Exodons, Emperors, Silver Dollars, etc.) might be more problematic.

In my opinion, these apistos are "easier" because they can survive in harder water. However, they are still very fussy about tank maintenance and it takes a lot to get them into breeding condition (in my experience). Good luck.

I bred cockatoos in a community tank with tetras, bolivian rams, corys etc.

Yes , though it's a bit crowded for my liking. You'll be surprised at what effective micropredators tetras are.

I usually had a small shoal of 6 to 8 cardinals in the tanks I bred Apistos in

Sounds good, maybe have a bristlenose pl*co and/or a few corys too.

I think this setup will work. I had a similar setup breeding A. Cacautodies. These fish prefer to spawn in caves. For my aquarium I went to home depot and found some slate floor tiles made with pure slate. I broke them up with a hammer and laid them out in the bottom making many caves. I also put some small flower pots in there.

They never used the flower pots, but the females each had an area down in the caves. The other fish never figured out they could venture down there. Also I put java moss all on the top of the slate for a place for the fry to venture to hide and eat. It worked fairly well for me.

I wouldn't suggest putting the bottom feeders in though. Apistos will spend all there time trying to protect the eggs from them and they are more likely to eat them then tetras and such.