I've found the words and shaded in appropriately. They're not common words and the whole thing is something of an anticlimax. There's nothing in the title (though the shading reveals a related pattern) or the occasion (eg it's nothing to do with Easter) or anything about the crossword that might suggest the words.
Usual EV misprints - I agree there should be "a" in 16d, I think 13a should be two words or hyphentated, and in the proud tradition of EV they're now making mistakes in the solution to a previous puzzle - the wrong letters are made bold in the top row.