It's easy to say City can lawyer up, but to my knowledge there has never been a case at CAS where a club gave fake documents in order to get a license to play European football.
Let's start this off by saying they already got in trouble from UEFA in 2014 and they decided to accept those sanctions. This most definitely does not help their case. Then in order to not get in trouble again, they decided to lie and say they were receiving money from Etihad Airlines for their shirt sponsorship when the reality was that the owner had given the club about 60 million pounds. Whether or not they even paid taxes on this is heavily in question. Which as everyone here knows is an actual crime.
There are still other violations that haven't been decided on yet. Coincidentally one of them is that they paid one of Sancho's family members a large payment so that he would sign there when he left Watford. Another is that they paid Mancini and Guardiola using off-shore accounts, which isn't illegal, but City never reported those payments when doing their accounts so that they wouldn't have to pay taxes and/or report those as losses under both the league and European versions of FFP. Which again, isn't those managers fault as there would be no way to know how the board is reporting that money. There is no manager on this planet that would be allowed to look at stuff like that even if they asked.
The fact is that we don't know. But what we do know is that most everyone in Europe, and every other club for that matter really hates City and it is hard to think that will not play into whether or not their punishment will be upheld.