This is very strange behavior.
I have never lost ANY galleries or images - I can even access my old galleries from the previous t2i model. I've never had any problems saving images to any galleries. I switch between galleries frequently.
NOTE: The galleries ARE specific to the saved generator, so if you rename the gen, it WILL start new/clean galleries even if you use the same gallery name. By the same token, you should be able to access old galleries if you rename the gen back to the old save name, and then access the old gallery name.
ALL of my galleries are private - and nothing is ever voted on.
I have NOT noticed the image generation getting any better based on previous prompts/saved images (I wish it did!!!).
Unfortunately, because of the randomness of the generator, this is not really possible at this time.