In guwiki (gu.wikipedia.org), adding <math> formula like,
<math>\Delta H_{reaction}^\ominus = \sum \Delta H_{\mathrm f \,(નીપજો)}^{\ominus} - \sum \Delta H_{\mathrm f \,(પ્રક્રિયકો)}^{\ominus}</math>
doesn't work,
English formula works fine,
<math>\Delta H_{reaction}^\ominus = \sum \Delta H_{\mathrm f \,(products)}^{\ominus} - \sum \Delta H_{\mathrm f \,(reactants)}^{\ominus}</math>
Example article: https://gu.wikipedia.org/wiki/હેસનો_ઉષ્મા-સંકલનનો_નિયમ