Without looking at the stylesheet its impossible to decide if spans are unnecessary or not.
Code:
span {
font-weight: 500;
}
will have definitely an effect on spans.
Code:
div span {
font-style: italic;
}
will have definitely an effect on spans.
And both will not be listed in Sogil's reporting as they do not have a class.
@Hitch: would a plugin put any value which adds empty spans to <p> and <divs> and <h1>?