My take on it is Renault have a systems integration problem. I am sure that the performance and efficiency of their design will be up to scratch but the reported late first running of the Renault power unit rang alarm bells when I heard it. You just can't expect to throw these things together in a couple of weeks and immediately be up to 100% performance with 100% reliability. It's called bleeding edge technology for a reason.
We don' t know what the problems are. It could be a control issue, which wouldn't be the worst problem in the world as software fixes can be comparatively quick to implement. They might have uncovered some fundamental performance issues which will require hardware redesign. They might have some manufacturing faults. They could easily have all the above. Let's just say the engineers at Viry won't have problems getting their overtime authorised for the foreseeable future!