That is my point-of-view: unknowable ≡ indeterminate. As a matter of fact, considering the two, unknowable statements about the past and unknown statements about the future, the latter is forever forbidden to us by the laws of physics while the former in simply yet to be revealed. In that sense, to me, the "forever unknowable" is more unquestionably neither/nor and not either/or than the simply "now unknown""unknown now".
Of course, this assumes unquestionable comes in degrees.