I'm in the middle of a particularly hectic and difficult day at work so don't have time to look now. And I may be wrong anyway, of course. But from memory, there was something in the Der Spiegel stuff that quoted an email purporting to state a total Etihad sponsorship figure of £ X (I can't remember the precise figures). On the next line, a figure of £ Y was noted against Etihad's name and below that, a figure (significantly larger than £ Y) of £ Z against ADUG's.
IIRC, Der Spiegel somewhat disingenuously implied that this more or less had us bang to rights and proved that ADUG itself was to provide the cash direct, which would be a disguised shareholder investment in breach of FFP. Yet the interpretation would be equally viable that ADUG was to procure the funds from elsewhere. Indeed, given that (as PB said above) information is in the public domain that the Abu Dhabi Executive Council part-funded this sponsorship in the past, this is surely the more likely turn of events. And that basically amounts to a shareholder opting to fund an obligation of a business it owns, which is perfectly legitimate and happens all the time in the corporate world for all kinds of reasons.
If ADEC paying the lion's share of the sponsorship is what happened, there might be certain corporate law, accounting and tax ramifications in the UAE, but something tells me they'd probably be OK on that score. And it would be irrelevant in terms of FFP compliance so would be none of UEFA's business.