Thank you. I don't fully understand "album mode" or how google assistant could stop Poweramp from checking whether that album (audiobook in this case) has a bookmark stored in it...
but anyway it sounds like for now, I'm wasting my time just selecting different options.
I think I will just combine each of my audiobooks into one super-long file, since the global "Store/Restore Per Track Progress" option does seem to take effect in this case.
Podcasts are harder to deal with, since a new separate file rotates in (and an old one rotates out) with each new episode, but I'll just