Those leaks, debris ejection and the (mild) loss of attitude control seem to have started right after SECO. And that isn't very surprising because engine shutdown can cause huge disturbances (shock) in the engines and related plumbings. (I know this sounds contrary to intuition). So I wouldn't consider that milestone as a success, unless it emerges that those problems were unrelated to SECO or any other engine operation.
That could very well be the case. I can't be certain. However, it's also a well-known problem in engine design. High flow rate fluid lines like propellant lines are often protected against fluid hammers. That may come in the form of a gas reservoir to absorb the pressure spike (sort of like surge suppression capacitors in electronic circuits) or as a check valve connected to a re-circulation path (like snubber/flyback diodes in electronic circuits).
The reason why I said it sounds counterintuitive is that I suspect that the flame extinction inside the combustion chamber also causes strong mechanical shocks. However, I don't know how that works and I could be mistaken.
