There is no difference in your formulas OpenSymbol/Arial because you didn’t change the font in Math. Both are displayed in OpenSymbol.
You can however improve legibility of tour formula by adjusting padding space above and below it (I find Math computes too strict a bounding box which frequently clips glyph extensions).
Spacing and select
Category Borders There you can give some “breathing” to your formula: I set Toip and Bottom to 0.10 which reveals more of the top shape. Experiment to find the optimal improvement.
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