This is a direct quote from the Boeing 744 QRH.
Procedures Beyond the Scope of the QRH
Introduction:
It is rare to encounter inflight events which are beyond the scope of
established non-normal procedures. These events can arise as a result of
unusual occurrences such as a mid-air collision, bomb explosion or other
major malfunction. In these situations the flight crew may be required to
accomplish multiple non-normal checklists, selected elements of several
different checklists (applied as necessary to fit the situation) or find little
or no specific guidance and need to rely on their own judgement and
experience. Because of the highly infrequent nature of these occurrences,
it is not practical or possible to create definitive flight crew procedures to
cover all events.
To have Engines 2 and 3 REV "Amber" (unlocked) warning lights, then have the inboard and mid LE slats retract, and then have a stall warning at rotate is beyond the scope of the QRH. This scenario is not something that forms part of any check or training in the simulator. The situation required them to rely on their own judgement and experience. There is no definitive flight crew procedure for the combination of events they were presented with.
They had no time to diagnose, they had no time trouble shoot, they were straight into "mitigate".
As we know they elected to raise the gear. They also landed safely, and nobody got hurt.