There is a difference between asking an author to list tw/cw within the introductory post of a WiP and demanding they do so.
As a community, we must not do the latter.
Making demands on an author is the prerogative of CoG and they have made clear what they are demanding of the author already.
If you wish to ask CoG to start demanding such cw/tw, then you need to not only answer the question, why but answer the question of enforcement when going to Rachel or Jason.
Community enforcement is not going to cut it - the community does not (nor should it) have the power to close a WiP thread. This means the most that can be done is to flag the author and bring in moderation. At this point in time, I do not think this is a realistic ask. The moderators are extremely busy as it is taking care of everything they are doing now.
A Leader should not have the power to close a WiP, except at the request of the author or admin staff because the Work in question is under the author’s control and the thread is there for the author’s use. If a Leader does close a WiP thread then it would still need to be reviewed by a moderator, defeating the Leader’s prerogative in the first place.
This then leads to suggesting to the author a cw/tw section or format.
If the community is going to be doing this, such suggestions should be done so the author is shown how to do so, not just told to do so. What I suggest doing, is copy-pasting an example (such as @Dae-kalina 's wonderfully done listing) and then discussing in your ask, what the author can do to customize such a list for their work.
At that point, the community needs to respect the author’s decision to follow through or not.
As an individual, you can avoid that WiP in the future if the author does not include tw/cw but that is the most that should be done.
Honey attracts more than vinegar but even the hungriest bear will not always eat the honey offered it. At the point of refusal, only the refusal of you, the individual to read that WiP is left available to pursue.
I think this thread has progressed as far as it could, with perhaps, coming up with an agreed format to present to authors when making a suggestion for cw/tw.
Thoughts, @Gower?