I don't need to track whether or not I have any particular score to cast mage hand, light, or guidance. So why would I bother to do so?
By making choices to avoid needing that high ability score for the DC or attack bonus we are acknowledging that separate ability score and class spell list. It just becomes easier with an active choice to ignore the those details based on that spell selection.
With the CHA based EK and warlock multiclass example we know we can take jump as an EK spell and we can get away with ignoring INT for that spell. But we cannot do that with sleep because then we need to use the INT score to calculate the save DC. In making a choice to ignore INT we are still tracking spells by class, and keeping track of which we can take or not take; which is a good way to avoid MAD issues but still tracking nonetheless.
The multiclass rules tell us that we prepare spells for each class separately and therefore track those spells by the class. We can make that easier to manage and it is still happening.
In the EK case I read the text as wizard spell and see that as a spell on the wizard spell list. I interpret the qualifier your wizard spells as specific to the wizard spells the EK has learned through the class because it is used to indicate ownership from the lens of the class in which it is described, but I can see it being interpreted as any wizard spell the character has obtained from the wizard list. In either interpretation the spell is still being tracked.
2cp
