The full article describes sun >rise< and sun >set< through the gates. So seems you have to watch from one side or the other.
"Each year, the sun sets directly through the 15 gates of Phanom Rung Temple twice, between March 5 to 7 and October 6 to 8. The sun rises through the gates on April 3 to 5 and September 8 to 10."
not equinox dates btw