You could mention the matter of the expired permit. It looks like Newham are attempting to imply that even if the disabled bay was not correctly positioned on the ground in compliance with the traffic order, then you were still in contravention as you were parked where a Resident's Parking Permit was required.
Hoever you only have to answer to the contravention alleged and not some similar contravention. The PCN says "Parked in a permit space or zone without a valid virtual permit or clearly displaying a valid physical permit where required (dedicated disabled bay)". So the allegation is specific to a "disabled bay", of some flavour. Not just any Resident Permit Only bays.
I suggest you mark up a copy of the map that's in the evidence pack, show where you were actually parked, in relation to the the disabled bay they say is shown on the map. Scan and upload the marked up map in your evidence pack, to support your assertion that the bay is not where it should be.
Also in your opening post you've put the below. Did you include that in your submission to the Tribunal? It's worth a shot but I believe there is permission for the sign. See do they produce the authorisation. Actually is it in the evidence pack? If so then please post it up. That said, to the best of my knowledge we've never won a case against Newham challenging this sign where there is also a DISABLED legend on the carriageway. Maybe somebody else can produce such a case?
"Ground 3
The sign governing the bay is not contained within The Traffic Signs Regulations and General Directions 2016 nor have the Council obtained DfT permission to use it. There is no provision within the legislation to use the term "Residents" nor a permit identifier for anything other than a dedicated bay reserved for an individual disabled person.Therefore the traffic sign is a nullity and cannot be enforced, making the PCN invalid."