IMHO, the list of causes and factors could look like this:
1. Uncooperative atmosphere in cockpit
2. High speed landing with late touchdown
3. Bad manipulation with levers of TR
4. Lack of SOP action:
- FE: reports IDLE REVERSAL ON
- FE: checks Spoilers Auto Function, if it doesn't work, deploys them manually by lever
- FE: reports SPOILERS, AIR BRAKES DEPLOYED
5. Repeating useless attempt to TR
6. No attempt for Go Around
7. Engine mechanical interlocks - lack of maintenance or design fault
8. Lack of crew training
By my opinion, the red line is primarily cause of accident. Designers knew that there are some condition when automate system doesn't work. In those cases the FE action is absolutely inevitable.
Without spoilers, the breaking action of gears is very, very low, breaking force of spoiler is missing too and with light a/c in a crosswind, the WoW switches may not be activated. Without WoW, hydraulic of TR are electrically blocked... With good mechanical interlocks on engines, they cannot stop too, only their speed was lower.
Force for TR levers are about 3 kg, mechanical stop (TR idle) needs twice a more of force to overcome it. As supposed in our case, with unadjusted mechanical interlock on both engines, the force could be about 20 kg (Kulverstukas) to overcome it regardless of blocking.