It seems unlikely that a script is rejected solely because of formatting. If AMERICAN BEAUTY came packaged in unacceptable font with margins out of alignment and other peccadilloes, it would still be AMERICAN BEAUTY.
Anyway, there's no excuse for formatting mistakes. It takes no skill, intellect or talent to learn formatting.
Are four protagonists too much? Probably. If you're writing a spec script, the narrative should revolve around one character. Producers are looking for "star vehicles." One great role to showcase one great actor.
In THE MAGNIFICENT SEVEN, the protagonist is Yul Brenner - despite the other six titular gunslingers. In the original THE POSEIDON ADVENTURE, Gene Hackman is the protagonist - even though he's surrounded by a litany of Oscar winning actors. Even in "two-fisters" - like buddy comedies - there is just one protagonist. In RUSH HOUR, the protagonist is Jackie Chan - not Chris Tucker.
The protagonist is the character whose problem, journey and solution are all at the heart of the story. He makes the choices, has the best scenes, solves most of the problems and is in the middle of the climax.
Truth is that it's hard enough to write one fully fleshed out protagonist with an effective, meaningful and emotional transformational arc - let alone four.
It often results in a scattered and shallow narrative that is emotionally unsatisfying.
Your decision had a cause and effect throughout the narrative that sunk the script early on. (The reader kept asking himself, "Whose story is this anyway?")
Four protagonists coupled with bad formatting and, my guess is, the script appeared "amateur" from fade in to fade out.
