I don't think umpires should have to worry about the type of music being played, only if it's still being played when the batter is in the box. There are no official rules to walk up music (unless tournament made rules for it) just music ettiquite, which people tend to not follow, but umpires can't enforce ettiquite. In a 14u game especially, there isn't anything these kids havent heard or said at school so I wouldn't sweat it. Should the lyrics be clean...? Sure but why make a big spectacle if they aren't? I find it more irritating when teams dont follow basic ettiquite like the team warming up on defense inbetween innings plays the song and the offense does the walk up music. Instead sometimes you have 2 sides clashing music between innings and it sounds awful on the field.