A spiritual kissing cousin of such compellingly campy ’90s Aussie-produced extravaganzas as “Strictly Ballroom” and “Muriel’s Wedding,” director Gracie Otto’s “Seriously Red” disarms and delights as a sensationally spirited concoction that neatly balances unfettered outrageousness and unabashed sentimentality. The beating heart of the entire enterprise is Krew Boylan. As screenwriter,…