The tolerances are so bewilderingly massive for the very reason that stuff like this happens
Methinks you need to do a little homework study because whatever training you have had in weight control and certification is shown up to be sadly lacking by that comment. A few kilos isn't going to be a showstopper - one is far more concerned about the cg. Quite apart from the engineering concerns, there is the legal concerns should you be called upon to justify whatever shortcuts you may have chosen to implement or accept.
If a sensible analysis has gone into the loading system, particularly if there are LMC adjustments, and provided it is applied correctly, fine. Otherwise, you could find yourself with a cg problem without too much difficulty, obviously depending on where things are put in or left off and weights involved.