they specifically said that they did not want to put a number to the amount of endings the game had and that 17K number came from a journalist who claimed to have gotten hold of info from within Larian.
Huh, cause I never actually checked where the 17K endings claim came from I did a little digging and found the source.
So fwiw, it came from Fextralife's video, where he asked a/the Lead Writer of the endings, Crystal, "how many variations of the ending are there"; she replied with 17K. She also didn't give a number when asked for how many mainline different endings there are.
So maybe she was taking into account the hourish long scrapped ending cutscene.
With that definition in mind, maybe the current epilogue has technically hit/surpassed that number, even if it's just small differences?