With eight of these locomotives sitting doing nothing in Spain and two doing likewise in the UK, I think we now have to assume that Stadler is taking some of the risk with this project. Had the contract required payments on completion of construction, on handover to ROG, or on UK acceptance, it seems likely the manufacturer would have been much more aggressive in pushing to get the vehicles moved to the UK and approved for use on the network. And would be demanding payment by now, but with ten expensive locos sitting idle that would surely put ROG in a pretty parlous financial situation.
Sure Stadler could just be sucking up the costs / delay, accepting there’s not much can be done other than wait if there’s no work for the 93s, but if that was the case I suspect the firm would be trying to re-market them by now.