Well, I'd been working on a long response that seemed to get deleted, but I have a few main issues that I at least want to bring up.
For one, the old ghost lore allowed ghosts to be played in a variety of ways. You could become a poltergeist, which is on the spookier side of things (not as spooky as this current iteration, but they were those who rejected their death, grew angry, and haunted others), and specters, who accepted their deaths and pursued their existence as a ghost in an entirely different manner. Unfortunately, there is no substitute for specters in this lore. This is my biggest issue. Most ghosts on LotC aren't played as poltergeists (or what this lore makes ghosts). That's not to say they're not interesting, but they're a niche, and make the scope of playing a ghost extremely narrow. Ghost characters aren't all that common, but I suspect you'd make a number of them unplayable without including something very similar to specters, a ghost that is what we conceptualize as a ghost (corporeal, can turn invisible, floats) which doesn't seek to haunt others.
My second issue is with episodic and eternal obsessions. This might just be an issue with semantics more than anything, but this change seems to greatly narrow the scope of what ghosts are able to pursue. Does it need to be a very explicit, specific single thing, like saying goodbye to their son or finishing their life's work, or can it be something more vague? My hope is that creativity and flexibility is allowable here, and if so, then my concerns aren't well-founded, but I want to understand better.
My third issue is really just something I think the current ghost lore does really well that this lore lacks, as I think the three stages of progression for ghosts is really cool and something lost here. To start out wandering, unsure of your death, only to then have it confirmed and progress a step further, and then choose to accept or reject it... it's super interesting, and I would argue offers a great deal more compelling RP for ghosts than what you'd find here.
If it's not clear, my chief concern here is keeping some of the better aspects of the current ghost lore, like the flexibility and interesting progression still a part of being a ghost. I admittedly know a lot less about gravens, and have less feedback to offer for those, but I hope you'll still take this feedback into account. Personally, I've had plans to play my ghost character for a long time, and while it's a bit of a temporary thing, it's something I've put a lot of time and thought into. However, with this rewrite as it is, I definitely cannot play that character as it stands, or would have to do so in a manner that eliminates all the motivation for making him a ghost in the first place. I understand that it's self-serving, but I do think it's the job of the Lore Team and those who submit rewrites for lore to take note of those who actually utilize it and ensure that the rewrites don't harm them without cause, and I firmly believe that this rewrite does just that.
Also, I am curious what exactly warranted this rewrite. The current ghost lore is good (I don't know about gravens, again), and there is no consolidation here since both ghosts and gravens exist. All this seems to do is shift them from ghastly creatures to dark, spooky ones, and I don't see a ton of benefit to that.