Tbf to UEFA, and before people start frothing at the mouth about the injustice of it all, I feel I should point out:
i) The actual wording of the rule in respect of pre-2010 squad costs supported the method used in the 2012/13 toolkit, iirc. So, while we may have been screwed by the toolkit change in 2012/13, UEFA did have a defence against that, to some degree.
ii) This change in the toolkit, wasn't the only reason why, in the eyes of UEFA, the club failed FFP. They also raised a significant number of objections to some of the accounting treatments used by the club, including the inclusion of amortisation in the pre-2010 squad cost calculation (not just wages as UEFA wanted). Others were the revenue from Fordham, the revenue from the sale of IP to CFG and the fair value of AD sponsorships, any of which could have led to an adjustment of just the few million required to push the club into a breach.
My point being UEFA had plenty of other strings to their bow to push the club over the loss limit so that the pre-2010 squad costs would become irrelevant. So, it was as much in the club's interests to settle, maybe more than UEFA's, and then to claim the dispute was just about the pre-2010 squad costs. When, actually, it most likely wasn't.