like i said "it has all the features
I need" - &
I don't use one drive or need back sync.
but the real message is. there's an android app developer who responds to messages so ask whats on his to-do list and toss a coin to.. by buying the app if you want to encourage more development.
when first launched, that app only did cloud, not calibre CS. that got added due to feedback & customer requests.