The hydride-fluoride pyrochlore NaCaMg₂F_7-xH_x has been synthesized at high pressure (2 GPa) from binary fluorides and hydrides. Contrary to initial expectations, we did not find strong evidence of selective hydride substitution in special anionic sites. F-center formation under UV irradiation at room temperature was observed, demonstrating the potential lability of hydride and enabling further systematic studies.