That's nice and all, but your post doesn't really address any issues. It just seems like ego validation to make one's self feel superior/better that they did not have difficulties in doing something someone else did.

Do you have actual input aside from what was already offered? (stay in the middle of the room)

You probably need to wait for some rebalancing from CDPR. The expansion bosses seem all over the place currently. Having the wraith heal as fast as you're reporting is pretty nuts. No harm in dropping the difficulty unless you're set on getting some kind of achievement

THANKS TO ALL, I BEAT THE WRAITH

I had to re-spec Geralt for a DPS build. Got his base Silver to 6500. Before, each swing did 700HP damage. This time, each did about 2800-5000.

At fist I was upset to see that for whatever reason, her first tick from healing changed. Instead of +3900HP/tick, she was getting +5500HP. But having a sword doing 400-750% more damage did the trick. Igni, being the primary damage dealer for Signs, even when boosted to 325% like in my Sign build, just doesn't do the damage to Wraiths. (on everything ignitable, I can keep people in a perpetual firestorm until they die.)

After beating her, I took on the Manor's boss fight (no spoliers) and beat him on my first attempt.

I've since beaten the expansion, and have to give CDPR another Kudos on such a great story! They were not lying when they said it was the caliber of the Storyline they had for the Baron in the base game.

Can't wait for more!

Did a quick read of this thread, didn't read you use a sign build. Than again, pretty obvious that igni doesn't work on specters. The bestiary states yrden, though that wouldn't be useful with this wraith either as it heals faster than yrden does damage, asuming you have that specific ability maxed.
I was responding more to people having issues targeting the paintings. Though I have targeting issues too, I had none on the paintings. First swing was a hit every single time.

If someone else did it, I guess they didn't have any difficulties with it either.

Yrden is for pulling specters out of white-sheet mode.. the one where they touch you and damage you, even without attacking and take very little damage.
That whole doing damage thing is just an extra and frankly yrden isn't useful against a wraith unless they do that sheet thing... or keep teleporting around, which also gets annoying.