If you break down the written submissions City made at CAS 1 (
https://www.tas-cas.org/fileadmin/user_upload/Award_CAS_6298_internet.pdf p14) you can see the likely main strands of argument at CAS 2:
a) ...the Investigation conducted by [UEFA] was not conducted in accordance with procedural fairness and due process and was contrary to legitimate expectations; IRRELEVANT NOW AS CAS IS A DE NOVO TRIAL
(b) [UEFA] is not entitled to make any determination or to allege any breaches in respect of periods prior to the reporting period 2016-17, being periods covered by the 2014 Settlement Agreement; A KEY ISSUE
(c) [UEFA] is not entitled to make any determination or to allege any breaches in respect of any time prior to 16 May 2014 being five years prior to the date of the Referral Decision; ANOTHER KEY ISSUE
(d) [UEFA] is not entitled to make any determination or to allege any breaches of the [UEFA CL&FFPR] in respect of periods prior to the reporting period 2016-17, being outside of the current monitoring period; ANOTHER KEY ISSUE
(e) a declaration that the Swiss law personality rights of the Appellant have been violated by the Leaks and that Respondent is responsible for such violation; LARGELY IRRELEVANT
Win on b,c and/or d and the case appears to collapse. Lose on those and the case will be judged on the factual merits. I do believe UEFA will need to do more than wave the Pearce "we can do what we want" email extract around.