Got your Pm kiddo.
Well first of all, I would start off with using the size of pans called for, I take it she means the 9 by 2 inch deep pans, it looks like it is not a heavy riser so that makes a difference. Also, using heavy, not black coated non-stick pans makes a difference in how a cake cooks, that is true but at 325F that should have helped. Sometimes when you get into using the smaller pans for from scratch recipes, you won't get the true results that you would get if you used the pan size called for. I have the same problem for a couple of other from-scratch cake recipes, it just affects the way they cook. It does work in some cases but it just isn't going to be as consistent as it is with cake mixes following package instructions.
I would stick with using unbleached flour, not sure if you did or not and though with some cakes there is not a noticable difference there is with others. I can tell the difference in many cakes I make when I substitute the regular all-purpose when unbleached was called for.
Not certain if she called for sifting flour before measuring or what but that can also make a difference in that once flour is aerated you are using less flour than if it is compacted in your container.
I only use whole milk in cakes, there is a huge difference in the outcome when using 2% or skim milk. Not sure if that is a factor. Yes some people use the other milks with lower butterfat contents but boy if you experiment and make them with the various types of milk, you will see a big difference.
Overbeating or beating at too high a speed is a major issue with from scratch cakes. Once that flour is in there you can really damaged the molecular strands of your cake batter if you beat too high or too long. There is also an issue if you underbeat your eggs, fat or sugar.
I have been searching for 40 years for the perfect white or yellow cake, chocolate was easy to find, so were a few others. But even though I have made many good yellow or white cakes I have yet to find the perfect yellow or white cake. I think a white cake that has buttermilk, cake flour and shortening is the way to go for the lighter more moist white cake from scratch, butter will make it too dense. For a yellow cake, look for recipes with oil, butter is best for flavour but you will get a very dense cake when using butter.
I am not a cake mix fan, I find them too sweet but then, I was around when they first came out here and I actually think they were much better in those days. I find them also too spongey or a texture that I just don't care for. Having said that, I still will turn to a cake mix for most white or yellow cakes and doctor the heck out of them. I prefer a white cake made only with eggwhites, no yolks. I do use the White Almond Sour Cream Cake recipe on this site. I also use Auzzie's Extendacake for white cakes and it is the only one to which I add butter and find it works out well.
I would have to go back and take a look at that recipe again but the one thing I might try as an experiment with it would be to switch to buttermilk for the milk called for. Now buttermilk is usually 2% but it has a totally different affect on some cakes. However if you switch, it does have an affect on acidity levels so normally where buttermilk is called for you need baking soda and I am not sure if this recipe calls for it or not. There would have to be a bit of tweaking with that.
Never refrigerate a butter cake, this can damage most butter cakes and dry them out and effect their consistency. Sometimes butter cakes do ripen and are best if sealed and then eaten the next day. That is also true with some loaves.
Not sure why she says it doesn't matter if the temperature of ingredients are room temperature or not, most times it does have an effect on how they cream and whip up.
You are never going to get the same texture you get from a cake mix cake and I am not sure if that is what you are expecting. A from scratch cake generally is more dense, you really sink your teeth into it, it isn't spongey unless you are making a sponge or chiffon type of cake recipe. of course, a cake made with cake flour will have a much more delicate crumb. But a butter cake is supposed to be dense.
Here is a thought for people that react to preservatives, an angel food cake is very easy to make. No fat, so good for people watching fat contents, less sugar than most recipes too. Only disadvantage is that you cannot decorate it in quite the same manner but you can use stabilzed whipped cream and can even cut a tunnel in it after you torte and put a filling made of fruit. It is possible to use a buttercream on it, preferrably something whipped like the Whimsical Bakehouse Buttercream. There is nothing like a homemade angel food cake, they are quite something and very easy to make, light and fluffy and moist.