Earlier quoted context omitted.
Just to make one thing clear: Before the treaty comes into force it needs to be voted on by the Euroepan parliament and national parliaments. Before the votes the treaty will be published. What is a highly guarded secret are the current drafts , not the final agreement. It's actually not really different from how most laws are written, especially those proposed by the government. While those are in the drafting phase…
If the deal is done in secret, people'll complain that its secret. If the deal is not done in secret, people'll complain about the draft terms before it is finalized.
"complain" just means negative feedback which should be taken into consideration since a draft is a version which is still being worked on. Isn't that how it should really be?