If you're intending to challenge the PCN, then it will support your case if you can print-off and attach copies of the entries you made on the parking app. To be frank, it is very unlikely the council will accept any representations you submit because they know that if they do this, >95% of people then just cough-up. We do, though, encourage people to submit them, because sometimes the council reply is unacceptable in law, (i.e they shoot themselves in the foot).
There may also be a 'technical' defence, unrelated to the alleged contravention, based on council mismanagement of the enforcement process, so wait a bit to see what may be suggested.