Just throwing it out here, what if 2 'trusted' sources use different names?
I would stay with the box, but be sensible about it. Dont overthink things what often happens when discussing it on fora.
We will need a place to record specific examples, perhaps we can make a thread someplace to put examples. Decided by staff or you guys, and then link to that thread from the Style Guide in the Game Titles section.
But I don't think we would need to go through the entire list to determine a consensus. There would be a heirarchy. We would have a general order, and a specific order. For example, Sega/Sonic Retro should be the priority for Sega games. Anyways, think of it like so (in general) :
If the game is on Mobygames, call it by the name they use. If it is not on Mobygames, then look on Gamefaqs. And go down the list.
However, it isn't to say that people will need to visit all of these sites to look up what to name their games before adding them. As you said, no reason to make it more complicated.
This scenario may not even present itself that often, as we have a large percentage of games already in the DB. It is more likely to come up with people updating existing entries.