The sunlight's Int scaling does not affect Miracles, only dark Miracles. Because of the int scaling, it's spell buff will be higher but the numbers you see only apply for Dark, so it's non-dark spell buff is actually lower than the canvas talisman.
The only 2 Catalysts that breaks this rule is Crystal Chime and Itzals staff, which is unique in that all spells scale with both int/faith and thus making it's spell buff the only one that correctly displays the right spell buff.
You can test these out yourself, Sunlight will always do about 15% less damage than the canvas despite higher spell buff. This is why you'll always see people with chime and Itzal staff on high dual builds.