your questions regarding the game rules (improving the interpretation).

The rules allow the player to pass to the left along the sand to break through the shifted Gate of the Overlord.
...

passing is allowed - adjustable(!) rules based on reality:
1) "flawed" generator
2) game physics (you can't pass through monsters and rocks - for the shortest path)

restores per block are somehow taken, but it is not described quantitatively anywhere - but still, common sense and the adequacy of the players overcome this ("transfer" this situation to the Gate of the Overlord).