Two issues with that.
Firstly, Greek myth is definitely not about cosmic good and evil. At all. Not even remotely. Like...it literally bears no relation whatsoever, on any level, with cosmic good and evil.
I didn’t say Greek myth was
about cosmic good and evil. But Greek philosophers absolutely conceived of good and evil as fundamental forces of the cosmos.
Second, the evils of the gods is likely at least a little exaggerated by playwrights, who were criticized by their peers for telling versions of the stories of the gods that make the gods look bad.
Sure. Point is, their gods were complex. Generally viewed as overall positive, but absolutely not unambiguous bastions of goodness.
More to the point, even the concepts of order and chaos aren’t even cosmic in the same way that they are in D&D or in a lot of fantasy fiction.
Chaos is absolutely 100% a cosmic force in Greek myth, and it is antithetical to the Gods (well, to the Olympians, anyway), and to the proper way of things - which is to say, order.
The gods aren’t the gods of Order, none of them are dedicated to Order as a high level concept, they’re just The Gods of Olympus, who overthrew the more wild and destructive titans.
The “God(s) of Thing(s)” notion is a very modern one, and not at all consistent with... basically any ancient religions, but
certainly not Greek myth. The Olympians were the Olympians. Complex and nuanced as any human. Certainly you would make sacrifices to specific gods for specific reasons, but to conceptualize them as “Gods
of this or that” is to woefully oversimplify them.
If you present a world in which there are Gods of Good, as such, and Good is a cosmic force that matters, then the Gods of Good must actually be Good.
Sure. My point is that there don’t need to be Gods of Good for Good to be a cosmic force that matters. If you like, think of it like Goodness itself
is the “God of Good,” and all Good-aligned gods are lesser Gods that, in a very literal sense, owe allegiance to it. Allies of Good, not embodiments of it.
But, I digress. To reiterate my answer to your question, yes, I can see how moral ambiguity in Gods of Good in a setting that has such things is internally inconsistent, even if it’s not a setting conceit I much care for.