pls don't get annoyed but
..if it were possible to have an attitude reference of last resort (or be able to switch to known good source...yes I know), would a big button which did no more than try to get wings level and pitch to +3 degrees an impossibility ? It would have to have control algorithms built up by extensive testing of modelled upsets, take very conservative assumptions about the control deflections it could apply, and leave throttle settings to the pilots). Might be a compromise (does the right things in this scenario but not that, acts too slowly in this case etc) but better than guessing when disorientated ?
If this is rubbish, pls laugh and then delete.
Still like vertical gyros but these were only good for a a few seconds in an accelerating environment (where it could no longer find 'g' and correct itself).