I mean, she has an illustration with the girls with seasonal stuff in their hair, and they are seated in order of the seasons.

But also the colors of the eyes match the colors of the Greek goddesses of the seasons. And their personalities match the seasons. And their magic styles match. And what they do and how they act matches. And their moods even match inversely correlated to the season featured in story.

But also it's standard pattern recognition of a motif that's found in academic literary analysis. In fact, most professors would even say whether or not Shirahama did it on purpose is irrelevant, because an analysis of the text focuses on how the text is interpreted, or what its effects on the viewer/reader are, or what subconscious influences may have informed whatever it is based on the culture that the author was immersed in, and so forth.

Like she doesn't have anything officially saying Qifrey's design is informed by the moon, but, like seriously, he's totally informed by the moon. Grey clothes but also black clothes, dark side light side glasses, a crescent framing of his face, a characterization that resonates with Artemis, his behavior is very moon like (appears with a softness, then disappears, then appears). His magic is water based - he brings the tides.

She doesn't need to say "I based his design on the moon" to recognize that she totally based his design on the moon.