I agree with others, that there was no reason to do any of what's being claimed.
No reason for Abu Dhabi to hide their ownership of City when the takeover happened. Which has been subtly and not so subtly implied since the start of the ownership
No reason for Sheikh Mansour to need to dip into his own pocket to pay Etihad's (a wealthy state's own airline) remaining balance.
No reason to hide payments to Mancini what would have made very little difference to FFP break even requirements, other than risking being sanctioned by UEFA and the PL. I haven't even seen much about the player image rights issue, I take it that must mean it's either a similar story or we just don't have much info on that.
The looser fit and proper owner tests and non-existent FFP constraints in 2008 would have made it much easier than Newcastle's bid, which still got through. As far as I'm aware, there were no failed bids from Abu Dhabi or a related consortium, which would mean they didn't even test the waters. If you really think about it, even if Sheikh Mansour's private ownership was a front. He could and probably would have sold the club to them at any time afterwards. Perhaps in 2011, when Qatar bought the remaining shares of PSG. At that time, City had likely got their valuation on their FMV and would have worked out the roadmap already.
If it was a disguised ownership, where they foresaw all the things that the people with tinfoil hats are giving them credit for. Bearing in mind, they would have had time to prepare for FFP since 2009(where FFP was agreed on) and if I remember right, City employed someone who helped write those rules also. If all of that were true, then it stands to reason that there would be no need for people to chase up remaining balances from Etihad on City's side because that's one of the first things they would have ironed out. How can anyone believe they planned in advance for so much, to hide their tracks but tried to wing it on one of the biggest aspects of FFP?
"Build-in some back-up contingencies for our dodgy sponsorships, for the club we secretly own? Nahhh, we'll just deal with that when we get there and have lots of back and forth, leaving paper/email trails everywhere. It will be fine."
Maybe "no reason" is a bit too strongly put but on the balance of risk vs reward, all I find myself asking is : "In that scenario, would they have thought that was a necessary risk or not?". When all is said and done, everything that has been claimed to have been done, could have been done without breaking any of the FFP rules, to my mind.