Thing is Jam should never be rainbow colored, but a baked good can be almost any color you want with if you're willing to put in the effort regarding layering with no ill effect on taste since it's just food coloring. In fact "rainbow cake" is straight up a thing sometimes including the icing as well (google image search it for too many examples to count), the icing job on that is a bit sloppy, but overall their doesn't seem much reason it wouldn't taste like delicious cake assuming the base recipe was correct.
Fin...... Yeah.......? What's with those eyes?You've got something to say?Not reeeally......Kept you waiting! I have brought a cake with me!Wha-?! That's quick! She was out for just a moment and she's already done baking one?!You're saying she can bake one up even faster than Irako...?! 'Toga!So even something like that is within your field of expertise?!This is my special-made cake!Please enjoy yourself!...Oh?American~The colorful layering penetrates even the inner part and the taste is like that of sugar itself.
...A few days later, the Admiral came down with diabetes.