We're making videogames! I need serious advice

I think you should definitely use the home field advantage if it will make the game enjoyable. The reasons “international” releases often don’t include Spanish don’t entirely apply to original releases. I suppose getting enough sales to turn a profit is an issue, but it’s an issue anywhere anyway.

I also think, don’t worry about silliness, either (consider me biased). It’s okay to move off an aesthetic if your goal is to make money and you’re not making money. But an aesthetic of silliness has worked out pretty well for a number of game and technology businesses. Besides, “If you’re not embarrassed by the first version of your product, you launched too late.” It’s one thing to already not have money, but it’s another thing to run out of time.