I've accepted people's guild cards, logged off, and then logged back on to no longer have their card. This has happened to me twice. I know I haven't accidentally hit 'No' on accepting their guild card as I've used their card to search for them later in my play session.
Also, my guild card language is JPN, but see no way to change that.
Also, my guild card language is JPN, but see no way to change that.