After digging a bit, the first BattleTech record sheet published back in 2003 was in RS:MWDA1, listed as tech level 2/3132. That is most likely why it was listed as Dark Age. Also, looks like someone updated Sarna yesterday with the TRO3050U info.
I suspect the writers of that record sheet product didn't think too closely about the dates, instead used dates when the 'Mechs first appeared in MWDA. The CPLT-C2 is in the first MWDA novel, set in 3132, though considering the setting at that point, it seems implausible a small militia (its user in the novel) would have a brand new 'Mech.
The date as added in MUL is much, much more sensible.
And all this MWDA talk makes me sad that it is unlikely we'll ever get a Mechwarrior game set during that time. So many cool 'Mechs and a lot of tech...
Though i suppose that if MWO goes long enough, they will start adding later 'Mechs too. But then again the fact they're making MW5 and it being set in 3025-3049 (and the inevitable Clan Invasion DLC/expansion/sequel if it does well enough commercially) makes me think they'll focus on 'Mechs available on that era as much as possible to maximize amount of shared assets.
Also gotta say i'm supremely disappointed in MW5 pre-order bonuses. Early access or betas are not my thing (prefer to play something more polished), and all the other bonuses relate to MWO, which i stopped playing. My last attempt was last spring, the new city map's performance put me off the game along with its continued issues and unfulfilled promises (i'm a founder).