Yes, you can do that, so, let's assume you already have a color option with a formula, so something like $ci(color, 0)$ to select the color of the next event using CI function, then, if i understood you correctly you want to do something if the even is currently taking place, so, $ci(start, 0)$ is when the event starts, $ci(end, 0)$ is when it ends and $df(S)$ is current time in seconds since epoch, so writing this:
This shows me the first event (at the moment an allday event) and formats the day in capital letters. the same formula for the second event shows a start and end time.
In a second line I do have the event itself:
$tc(ell, ci(title, 0), 32)$ - $ci(loc, 0)$
But 1 thing came just in my mind: I do have in the globals set, that if LightUI the text is dark and when DarkUI the text is light. This changes automatically after 22h and 8h in the morning. So I can't set an active event to another color.
Just outputs the color, you need to use it in the color preference of the module or between bb code tags like [c=$if(df(S) > ci(start, e0) && df(S) < ci(end, e0), #FF0000, ci(color, 0))$]MyText[/c]