It creates an extra timer but it runs in the message thread, so I would use it for audio stuff, and actually since ScriptPanels also have a timer for animation it became pretty useless - I think I added it before I added timers to the Panels but left it in the code base for some weirder use cases. Somehow the API doc didn't make it in the autocomplete list, but this is the usage:
const var timer = Engine.createTimerObject();
timer.startTimer(150); // in milliseconds
timer.callback = function()
{
Console.print("tut");
};