It was that way in my November 2021 trip. The New York section had 11 & 12 and the Boston section 10, though I am not absolutely sure of the Boston section's sleeper car line number. I was in the 11 both directions and it was the sleeper closest to Viewliner diner, the 12 was trailing it (and was a V2). I never walked forward inside the train and only walked by the Boston sleeper at Albany when I walked back from watching them combine the sections (I watched the split from the footbridge heading east). I glanced at the car line number of the Boston sleeper, but I am not positive now it was 10, like I am 11 & 12 for the NY sleepers. I recall being a bit surprised when 11 was the first NY sleeper.
Perhaps someone in Massachusetts or upstate New York could verify? I don't get back there much, though I'll be riding the LSL again in November and will try to remember to check it then.