Hard to comment too much without seeing the board, but if there really is signs of thermal damage to the DB then it probably is a fair unsatisfactory and the process of replacing the CU will fix all the others in any case - I'd be more cautious in vetting the quote they put in for making right.
However, since it's more fun picking holes in other people's reports than doing my own:
Is there really an RCD six monthly test notice at or near CU as they've ticked in the schedule? Seems unlikely, since there isn't apparently any RCD protection on any of the circuits?
Is the inspector NAPIT? Their Codebreakers book says C2 for non-RCD cables in walls, although most other guidance seems to disagree and consider it a C3
I'd agree that a 6mm cable earth would be at most a C3 for a 60A supply (assuming all in good order) - you could do the adiabatic calcs and it would almost certainly come well under that, in which case no code but a comment to show I'd considered it.
Similarly pretty sure the Best Practise Guide says 6mm bonding is fine, as long as there is no sign of damage.
The only C2 I'd give for the missing RCD is if it's a ground floor property/flat with obvious sockets that could be used for outside equipment.
They seem to have ticked to suggest that supplementary bonding is in place in the bathroom - otherwise that would be a C2
So even though it might be harsh, it looks like it would still end up with some C2s anyway (assuming there is signs of thermal damage, which is quite possible).
Compared to many EICRs that have been posted on here, this one seems pretty good tbh. Not really a fan of the layout, (bit too cartoony for me and not sure it really makes it easier to read for anyone) but that's a personal thing.
At least here aren't many circuits, so relatively simple to swap out with an RCBO board and not that expensive even if you went with an 'expensive' option like Hager.
Just make sure the letting agency run any quotes past the owner before giving someone the go-ahead to stick in a screwfix special.
Having said that - the inspection was apparently done on 4/11? In which case the 28 day rule would mean that things should have been corrected by now??