Well, if we give a moderate rage boost on top of SSJ2, then 2x can work, it just was not 2x for CGs Gohan. I like the rage boost theory because I din really think there's a big gap between Goku and Gohan as MSSJs in the CGs, I think it was a noticeable, moderate gap, but nothing big — nothing like Goku vs Ginyus. Boo saga Gohan was stated to be way, way weaker than his CGs self... But if SSJ teen Gohan is still strong enough to fight on almost equal terms vs someone ~ Cell (level used vs Goku) — Dabra — I think Boo saga SSJ Gohan is like CGs Goku's level... And the big gap between his teen and kid self becomes more apparent as SSJ2.
Also, since Vegeta stated that if Gohan got enraged, that there would be no way to tell whether their superiority over him would be still apparent, with Goku reinforcing that an enraged Gohan is unstoppable, motivating him to release it all vs Dabra or in case Boo awakened... I think the manga suggests there is a difference between SSJ2 teen Gohan and an enraged SSJ2 teen Gohan at least... Which I think could possibly mean this rage pushed CGs Gohan somewhat above what simply the SSJ2 multiplier would leave him at.
CGs
MSSJ Goku : 100
Cell (vs Goku) : 110
MSSJ Gohan : 125
Cell (vs Gohan) : 132
Cell (full power) : 180
Super Perfect Cell : 270
SSJ2 Gohan : 300
Boo Saga
MSSJ Gohan : 110
Dabra : 110
SSJ Vegeta : 135
SSJ Goku : 165
SSJ2 Gohan : 220
SSJ2 Vegeta : 270
SSJ2 Goku : 330