Sune and Stefan, thanks so much for your suggestions.
Per Stefan's tip, I just looked through the house records for most of the 10 parishes in the old Älvdals district (härad) and couldn't find her. However, a few of the parishes, such as two near her previous home parish of Dalby - Norra Finnskoga and Södra Finnskoga - don't have records dating back that far. So, perhaps that's why the more specific parish name wasn't listed - the larger district name was used instead?
Per Sune's tip, the two names are so close (Elfdahlen as recorded and Älvdalen the actual parish) I don't think i should rule it out yet. Also, there were no other "Elfdahlen" entries in Fryksände's house record at that time, so perhaps that could indicate it was a little farther away - not an adjacent parish.
So, I still haven't been able to fully resolve this one yet, but thanks for the help. And in looking into this deeper I did just learn there's an old Norse language still spoken with a similar name - Elfdalien - so I can't help but wonder if she might have spoken that!
Regards, Mark