I have used rebuilt accumulators for early Rolls-Royces but they were meant to be disassembled.
I can see how someone could recharge the nitrogen pressure but there surely would be no way to repair the leaking diaphram that lost the original gas charge.
I wouldn't waste my time on anything other than OE MB or Lemforder. Maybe Febi-bilstein, also.
Bosch Master, ASE Master, L1
33 years MB technician