A family nurses an injured Angel that crashes onto their summer cottage roof back to health, hiding their foreign guest’s wings from curious neighbors until what injured the Angel returns.

'The premise requires a major suspension of disbelief. The logline raises more questions than it answers.'
I don't understand how these things are a problem? Firstly a logline is an enticement, posing questions that you have read the script to find the answers for. Secondly, you seem to be suggesting that suspending their disbelief is something an audience will be incapable of.

Again -- just an idea:

'A wing-clipped fallen angel must re-earn their place in heaven by saving the soul of a suburban family's teenage daughter who has fallen in with a nefarious crime ring.'

Good luck again.

If the angel has been THROWN out of heaven and can't re-enter until they have learnt some key moral lesson it could find some wings ;)

What if the Angel is like a troubled teen angel -- and in the family they fall upon there just so happens to be a similarly troubled teen who also has a big lesson to learn... etc etc etc..? Just a thought...

As dropped by LoglinesRUS, there are echoes of 'Michael' here -- but there's potential for a new spin on the concept; it's just that this 'spin', whatever it is, needs to be presented in the logline -- I don't think a family 'nursing' an angel back to PHYSICAL strength is interesting (or plausible) enough atm...

Regardless -- best of luck with it.