What would a thriving progress movement look like?

A wonderful initiative, best of luck with your book, I’m already looking forward to it!

I believe there are two-fold hindrances for wider acceptance and adoption of such progress-positive ideas, which of course come back to things already mentioned in your posts, and in comments to them. 

First of all, the 18th-19th century progress movement came on the back of tangible progress on multiple fronts of society, from population growth, technological development, increasing military/political strength vis-a-vis the rest of the world, and broad-based improvements in income and quality of life across the population. All of these things in their own way supported an ideology of optimism, growth and progress; since everything was actually improving, it was quite natural to believe in further and greater progress too. 

Yet, most of the same trends today are either stagnant, absent or even on negative, rather than positive, trajectories. In that sense, a generally positive or optimistic outlook is that much harder to come by, even in a more narrow technological or scientific sense, where progress remains clear. In another way, this perhaps means that an optimistic philosophy of progress could also be more valuable than ever, if it should supply reasons to invest and work for the future despite a bleaker outlook. 

Secondly, much less importantly, progress or progressivism as words may have certain political connotations among many people, which may in some cases deter interest or adoption due to confusion or association with politics (and in other cases be a positive factor). 

Personally I am currently very interested in the way ideas and values can guide broader success and failure of societies - as such this seems like an extremely interesting project! The way I see it one of the key problems in the west presently is a broad lack of positive vision and future expectations, on the back of the troubling trends mentioned. From your post, it obvious you’re aware of the same issues and looking to solve them. A philosophy of progress could be a key part in of amending the situation, thus immensely valuable. 

Progress studies is really interesting to me, because if one actually believes that it has a >0 chance of working, the EV is so huge that we should be directing huge amounts of funding towards it. As we are not [0], this implies that most organizations/people either think it has no chance of working, or haven't heard of it. 

There's an analogy to be made to internal tooling at most companies. All companies I've been part of radically underfund their internal tooling, even though it has a direct and quantifiable ROI. I don't know why this is. Increasing the 2nd derivative is so massively valuable that it seems obviously worth doing.

[0]: Where we = the government, private donors, universities.

This comment is not to be taken very seriously, but I saw something interesting:

In the description of the Bourgeois Trilogy, it identifies a new “dignity and liberty for ordinary people” as being the idea which drove the general increase in wealth.

I have on my list of books to read a different subject entirely which touches on this same subject. It is Eye for an Eye by William Ian Miller, about the logic of the lex talionis. One of the claims made in the book is that life among biblical civilizations or the vikings at the time of the sagas was more valued than the life of a modern man, and that justice was therefore much more expensive for people. The review I read contains the following quote from the book about the consequences:

Honor societies tended to be small and poor, and the cost of the tough virtue I so admire was in part their poverty; they seldom generated enough surplus to support lordship, let alone expensive governmental institutions. And they made sure that no one did too well for too long because that way lay serious inequality. Remember: they clipped the wings of those who were getting too big for their breeches. And prudent people might keep their talents and ambitions within limits that would prevent eliciting murderous envy from their jealous neighbors. This tough policing of the conditions of rough equality comes at enormous social cost – to innovation, to experimentation, to certain forms of productive ambition.

Taken at face value this produces an interesting trade-off between people's lives being too valuable to allow for the accumulation of much wealth or capital, and at the other end being to cheap to allow the growth of much wealth or capital.

Another claim that I see advanced which feels relevant to this question is that chattel slavery in the American South actively harmed economic growth there (and I'd be shocked if the impact wasn't more severe on the welfare scales).