Hello,
In first example you have animation inside cloner, so this way can be delayed animation for cloner, but in second example you have driven animation for cloner outside of cloner, so cann´t be driven by effector growing delay. Solution can be bake loft inside cloner (now it´s cloned object animated by keyframes) and use formula delay effector...
TimeOffsetWithFormula_DONT_0001.zip
Simply set cloner to one single clone, open timeline, drag loft into timeline, from Functions select Bake objects and bake all parameters.If checked, copy of original object will be created under original in cloner hierarchy, but itś keyframed. Remove from cloner hierarchy original loft, disable xpresso for driving progress and press play with enabled formula effector ;-)