It must have been surreal for Pratchett meeting Emma in person at the Snuff launch party. Since she voices the character herself, it must have been like meeting two separate friends at once - his writing correspondent and research partner, Emma, and his virtual guide/friend in Vilja.
That feels like a scene with the sort of bizarre, semi-irrational emotional undertones that Terry himself would often write about. I wish he was still around to ask how it felt.