What an awesome accidental find. Very red indeed, you don't see that very much. Cambodia seems to prefer peach colored wall paint on its temples, but the overall styles are very similar. I think relics of Hinduism remain because it was the previous dominant religion, and it along with older folk religions and beliefs get woven into each country's interpretation of Buddhism.
One little random factoid I know about Cambodia is that the King can not legitimately take the throne without a Hindu blessing. Because there are 12 or more Cambodians who are ceremonially Hindus, who carry out the rituals and customs, but don't truly believe in the religion nor practice it in their free time.
Thanks for sharing your accidental temple find with us.