Hello, it is the correct size 11 54 11 as that’s what is sold and used in the UK , i personally not heard any reports on our soil such seals being missized.
if the odd 53 size came on your forks (i wonder why!) , try to get that 53 size in your local seal stores. There will be something that uses a 53mm tube for hydraulics but i don’t have a reference to point to.
That NGK part number seems to suggest also a 45mm seal used on Suzuki 200cc bikes , but can’t trust Google 100%