If that is the case then the hat didn’t actually say “it couldn’t tell if Harry had any false memories.” It said it couldn’t detect deleted memories and seems to imply that ‘sophisticated analysis’ of all of his memories for ‘inconsistencies’ would be required to do so. The false memory given to Hermione is at the forefront of her mind and doesn’t require the hat to scan her memories (though Hermione could replay memories of event for the hat presumably). In addition the false memory is entirely out of character with Hermione’s personality which is something the hat, at a minimum, should be able to verify. Considering the quote specifically addressing foreign memory, it seems entirely possibly the hat may immediately detect the false memory for what it is.
Yes, I’m referring to the second bit.
If that is the case then the hat didn’t actually say “it couldn’t tell if Harry had any false memories.” It said it couldn’t detect deleted memories and seems to imply that ‘sophisticated analysis’ of all of his memories for ‘inconsistencies’ would be required to do so. The false memory given to Hermione is at the forefront of her mind and doesn’t require the hat to scan her memories (though Hermione could replay memories of event for the hat presumably). In addition the false memory is entirely out of character with Hermione’s personality which is something the hat, at a minimum, should be able to verify. Considering the quote specifically addressing foreign memory, it seems entirely possibly the hat may immediately detect the false memory for what it is.