Hockey-reference's adjusted stats are built on work done by others, such as Klein and Reif in their Hockey Compendium.
Yes, they're pretty good for forwards. I would say the biggest thing those stats can't account for is a change in coaching strategies that took place between 1985 and 1995. The change was managing forwards shifts to get the best scorers out for more minutes, in better offensive situations, supported by the best offensive defencemen. A result of this change was that bottom-six forwards played fewer minutes, shorter shifts, and were selected for their defensive skills more than their offensive skills.
The change happened because hockey coaching was becoming a profession, with coaching clinics and larger and larger coaching staffs.
Before 1970, forward lines played equally with every defensive pairing. Nobody was trying to leverage their top d-men with their top forwards. Third lines played regular shifts and scored like any other line. There were matchups and shadows but every line and pairing was basically playing the same game. Head coaches - with no assistant - set up the lines and matchups before the game and let things play out. Then you start seeing coaches like Bowman, Shero, and Neilson making changes within the game and finding edges in the 1970s. Phil Esposito, and later Wayne Gretzky and Mario Lemieux, play all the ice time they can handle. But by 1985, it's still not so different from 1970, with a few exceptions (see Gretzky and Lemieux). Lines 1-3 and pairings 1-2 are still basically playing the same game. In 1986-87, the #2 scorer has only 108 points.
By the late 90s, the changes is complete. Every team* is having their bottom 2 lines skate shorter shifts and try not to get scored on, and feeding their top lines all the best offensive minutes. Teams with more talent than money like Colorado and Pittsburgh save money on their bottom 2 lines by getting rid of offensive depth and riding their stars. And individual scoring became more and more detached from league scoring levels.
*except for Detroit, where Scotty Bowman is throwing it back spreading his talent and opportunity over 4 lines.