In the Harry Potter films, we can see several times something similar of what happened between the Harry Potter and Lucius Malfoy wands. Isn't this Golden flame just a phenomenon (and not a real spell) that arises during a strong duel between two wands?
If this Golden flame really exists, isn't this what happens when a wizarding child (that still doesn't know spells) try to use a wand? Or what happens are just sparks?
Are you kidding? This does really exist in the books, and it is an extremely powerful spell, withou any known incantation, so for any child that could perform this would be impossibly powerful. This elaborate and unimaginably powerful spell was cast by Harry's own wand, acting of its own accord.