On the drawings and from description - it looks like accumulator pressure is retained in rear circuit only, there are seals between both pistons isolating it from each other.
Booster piston can apply few milimeters of pressure on the back of master piston to support operation of front brakes, it cannot drop any further forward.
So, no - it doesn’t look like burst of front brake hose would drain the accumulator. It would cause loss of pressure in accumulator and would trigger pump operation (pump fed from separate section of the tank)
Now.it is time to wait for Kirbert and his keen eye for details to confirm/deny it 