Comprehensive rules 711.4 has your back. The important section is underlined.
711.4. Each face of a double-faced card has its own set of characteristics.
711.4a While a double-faced card is outside the game, in a zone other than the battlefield, or on the battlefield with its front face up, it has only the characteristics of its front face.
711.4b While a double-faced permanent’s back face is up, it has only the characteristics of its back face. However, its converted mana cost is calculated using the mana cost of its front face. This is a change from previous rules. If a permanent is copying the back face of a double-faced card (even if the card representing that copy is itself a double-faced card), the converted mana cost of that permanent is 0.
So you got different answers because previously the answer would have been 0, but now the CMC of Insectile Aberration is 1.
Private Mod Note
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“Tell me who you walk with, and I'll tell you who you are.” Esmeralda Santiago Art is life itself.
Two LGS judges provided two different answers (zero and one).
GR Tron - hardcasting Emrakuls and playing Forest in the sideboard
URB Grixis Delver - Bolt-Snap-Bolt
So you got different answers because previously the answer would have been 0, but now the CMC of Insectile Aberration is 1.
Art is life itself.
When did this change? I got the different answers within a week from one another, ~2 weeks ago.
GR Tron - hardcasting Emrakuls and playing Forest in the sideboard
URB Grixis Delver - Bolt-Snap-Bolt
Former Rules Advisor
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GR Tron - hardcasting Emrakuls and playing Forest in the sideboard
URB Grixis Delver - Bolt-Snap-Bolt