My Halo 4 stats page here on Waypoint still show the Crimson DLC achievements as all being locked but I definitely have 3 unlocked at the moment.
Also other users we have this problem… There do not appear the new achievements (Crimson Map Pack) in HALO WAYPOINT (Career Waypoint), only 49 original achievements. HALO WAYPOINT Xbox 360/HALO WAYPOINT Web.
A greeting.