"_Not_only_was_it_already_a_much_improved_agreement_from_ the_start_,but it kept being modified from the initial public version of it to the one that was finally sent to national parliaments."
Either the writer of this is an expert on the topic, well-known in the field and the weight of this judgement on its own is a valuable primary source; or, the writer is referring to such an analysis conducted by other experts but has not bothered to include a citation/link; or, the writer has their own critique but instead of presenting _that_ has just stated an opinion which they know to be controversial.
All of the above possibilities contribute substantially to the noise around any discussion.