This is a simple English language question. DGR 4.2 shows in fine print “with 5% or less free sulphuric acid\". The submitted DGD shows “with not more than 5% free sulphuric acid\". The meaning is the same. There is no problem in accepting the shipment.
DGR 188.8.131.52 states, although it is preferable to duplicate what is shown in DGR 4.2, there is no problem even if singular or plural form is used in the PSN, or the order of the words are reversed, or whether British or American spelling is used. Furthermore those in fine print are descriptive information which is not part of the PSN. Even if the words “with 4% free sulphuric acid” is shown, it is acceptable as it is within the 5% criterion.
English expressions are different from Japanese. By saying “more than 5%” or “less than 5%” you are excluding 5% from the bench mark. If you want to include 5% in the bench mark, you need to say “5% or more” or “5% or less” or more precisely “equal to 5% or more” or “equal to 5% or less”.