>>279651494
One answer could be that it aims for the wrong kind of stylization given its genre and target audience. People don't mention this, but a lot of careful consideration goes into designing the eyes in anime and manga. Settei will often feature multiple drawings and instructions pertaining specifically to the eyes (see next post).

Magical girl shows are kodomo shows that emphasize the youth and cuteness of the characters, and as such the eyes are usually given a big doe-eyed, jewel-like design. Outer corners of the eyes "droop" downward and overall roundness of eye and inner components are emphasized to give a gentle look (known as tareme). The irises take up nearly the whole eye, the pupils are blown wide and dilated, if not outright subsumed into the rest of the eye/eliminated. Highlights are strategically placed to give the eyes life and emphasize "cuteness".

Has its deepest and purest origins in the stuff Tezuka was drawing, e.g Bambi, his shoujo works from the 50s etc. Compare pic related left with right, a relatively modern iteration of a show like Precure.

It is actually kind of hard to get right unless you're studying directly from the source. With Spyce the eyes are large but their design is seems plain compared to anime. I think their mistake was making the pupils much too small and too conspicuous, the irises themselves could be larger and wider too; an extra highlight could be added. Also the eyes could be inched further apart.
You would then need to make a few other adjustments but I've gone on for long enough.