Bazz-B was able to last several hours with no issues and fight Haschwalth. Soon is a very relative term. And wounds don't really matter with the Auswahlen. NaNaNa was wounded and unconscious and still survived.

And again. Yhwach most likely doesn't care. He already took their soul pieces. There is nothing he could take anymore. He was interested in getting his sleep. We also don't know, how Yhwach defeated them. He could simply used the shadows to wound them. Yhwach always kills people in a specific manner. He explodes them. That didn't happen with Liltotto and Giselle.

The purpose of the Auwahlen is to take the power away from the Sternritter. Giselle, Bazz-B, Liltotto and Lille already lost their powers. They simply cannot be targeted again.

Bazz-B's wounds are survivable. It doesn't matter whether or not he hold back. If the wounds he inflicted simply aren't that severe, then he could survive. Byakuya was shredded and survived. And Haschwalth would give Bazz-B even the tiniest bit of a chance to survive.

Even if Bambietta died again, Giselle could simply bleed on her again. And it's rather unlikely that Giselle's dead.

With Cang Du and BG9 Haschwalth may simply have been operating on the basis of his scales and judging that they should be allowed to survive. We also don't know if they got killed by the Auswahlen. They could have evaded it or simply tanked it like Bazz-B and NaNaNa. And BG9 is most likely the one repsonsible for the statues. No one else would posses such an ability.

People discussed whether the Arrancar besides Mosquaeda were alive or dead back then, the same way we're disussing the fates of the Sternritter. Afterwards it's easy to say that there were not hints, but back then it was the same situation.

If Kubo's willing to give one faction survivors then he probably will do it with the other too. It's simple as that. And no one cares about the grunts. It's always about the named characters.