The Blackberry wine I made is from FWK Frutta series. They come with two sweetening packs. I used one so far and that bumped the gravity to 1.015, or 3.8B. I'm assuming adding the second would push it close to 1.030 which seems on the level of a desert wine. I find it hard to believe people use both packs.
What was the SG before you backsweetened? I have Frutta Blackberry and Strawberry, which finished at 0.998 and 0.996, respectively. After adding 1 packet to each, the SG is 1.006. I'm bulk aging for 3 months, then I'll adjust sugar and backsweeten.
Why did I have different starting points and the same ending point? The strongest likelihood is stirring. I stirred both well, but sugar is thick and it's entirely possible that no matter how much I stirred, it wasn't enough.
After bulk aging, I'll check SG again. It's possible that either or both will change.
I'll be adding part or all of the second pack to each wine, based upon taste. In the past I've bottled immediately after backsweetening, but I'm going to put the wines back in the carboy for a week or 2 after the "final" backsweetening. This gives the wine time to meld.
Regarding sweetness, I purchased several bottles of a commercial Vignoles, and after buying spotted "sweet" on the label. Darn, I enjoy dessert wines, but sweet wines in general are not my taste. When I tasted the wine, it tasted off-dry. The wine is highly acidic, and the sugar balanced the acid so it doesn't taste sweet.
Both of my Frutta tasted far better after adding 1 conditioning pack, but both need more. Both tasted dry, which indicates higher acid than is apparent to my palate. In a couple of months I'll add glycerin and 1/3 pack to each, stir well, and taste. While I don't
expect to use the full packs, I accept the possibility that the wine may require it.
In addition to my regular winemaking notes, I have a "In Detail" blog that records my progress. You may find it useful.
https://wine.bkfazekas.com/2022-strawberry-and-blackberry-in-detail/
BTW - it just occurred to me that I should check the SG again
after I rack back into the carboy. The act of racking is also a stirring/blending action, and I may get a more consistent reading by doing so.