It definitely felt like the latter was not self-delusion (especially when Anki was asking me what the capital of the UK was, say). But I felt unable to communicate why it was not self-delusion,

Wild speculation: it's possible to notice that a node in a representational graph is well-connected and thus likely to be close to another node, without following any actual edges (this is very close to a general metric of familiarity but doesn't actually require representing that metric). Something similar might be going on in your head: you haven't retrieved what the capital of the UK is yet, but you know you know a lot about the UK.