It's not headless, and when it is (during an interregnum), the Church is not eclipsed. It is still visible and it continues to possess the marks.
In a normal sedevacante period, it is headless (well, except that Christ remains the Head of the Church during that time), but is not typically in eclipse. In this crisis, however, the Catholic Church is indeed most certainly eclipsed in addition to being headless (as in a sede period). Of course, the Church is visible by definition, but the true society that is the Catholic Church is hidden behind the imposter Conciliar Church. Most people wrongly think that it is the Church. Eclipse does not mean that the object is no longer intrinsically visible, just that it's hidden behind something else ... as far as most of the world is concerned. Yes, the Catholic Church continues to possess the marks, but the Conciliar Church most certainly does not.