This is by far the best tres leches cake if done correctly. I have made it many times just as a vanilla. Often times topping it with many fruits. Today I have make it substituting the vanilla extract for strawberry emulsion to make a strawberry tres leches and it worked beautifully. Nice pink color naturally which is always nice. I also substituted a little heavy cream for strawberry juice ( blended and strained) for the cake to soak up for extra strawberry flavor. Definitely should try in my opinion. Wish I could add pictures to show. 

I’m not familiar with high altitude baking, but some readers have found this guide helpful for adjusting my recipes.

Did you make sure to mix the egg yolks and sugar as well as the egg whites and sugar thoroughly? And did you also make sure to use large eggs? The cake itself is just a plain sponge cake, so your daughter is correct. It shouldn’t taste eggy, but sometimes cakes with a higher ratio of eggs (like this one) can have an eggy taste if you try it while the cake is still warm.

Cake is delicious and I’d say it’s the best one I’ve ever eaten. I would recommend putting the entire filling on/in the cake though, especially if you plan on eating it soon, because it was a tiny bit dry on the bottom. Other than that, this recipe is perfection!

I haven’t tried it, but as long as it’s one that substitutes 1:1 for all-purpose flour I think it will be okay.

You probably could, but I haven’t personally tried it so it’s hard to give suggestions for how to adjust the recipe. It may be best to search for a different recipe that’s better suited to what you’re looking for or at least use a chocolate sponge cake recipe in place of the one in this recipe.