Of course the PL has more "evidence". They have had access to much more information from the club, basically all the relevant emails (not just those leaked by der Spiegel in 2018) and, I would imagine, all the club's relevant accounting information over a much longer investigation. No-one sensible is claiming they don't have more "evidence".
The point is that, firstly, even if they have a hundred times as many emails, they still have the same problem UEFA had at CAS, which is that they prove nothing and, secondly, that the real incriminating evidence (in the very unlikely case there is any) would be held externally and to which they have had no access.
So, while a hundred times the number of emails may increase their evidential weight and some of the things discussed in those emails may seem incriminatory, that "evidence" will, imho, be trumped by the witness statements and financial accounting from external parties that the club can choose to provide, in the form and to the extent they want, to counter the PL's "evidence", as at CAS.