Neither the Irish names, accents, or landscape is integral to the plot, raising the question, how is this a world "where Irish myth lives"?
It's a complete coincidence, but Power Rangers Samurai has the same five elements, fire (red), water (blue), forest (green), earth (yellow) and air (pink). Forest and Air were Wood and Heaven in Samurai Sentai Shinkenger, so it certainly wasn't intended to match Mystic Knights, it just did.
Forest and Wood are the same, it's just that Wood has Double Entendre jokes in the West. Heaven was meant as Air, but the kanji for Air didn't provide an appealing visor design. The two are the same because Wood isn't exactly an uncommon Element Number Five.