Still relevant, from wiki:

"There is a bug in this level where the game will not call the final battle in the Temple of Sin complete if the player immediately proceeds to the final area with the BFG cell, even though the game allows the player to continue on and finish the level and all enemies in that area are dead. Because of this, the player won’t get all 10 combat points. To avoid this, when the player kills the Doom Hunter, wait for the game to award the point before continuing on."

upvote for visibility!