I will comment on your message regarding, which is for me a safer ground than philosophy.
Sorry for the very long answer i hope you won't bother anyway to read it and tell me what you think, if you have any comments.
As to your finding a way on "how to agree on phenomena" I totally agree. There was a moment (early 1900) where an objective language was formulated by the neue sachlichkeit movement (Tessenow, Muthesius....) in order to find a common language based on universal values as opposed to the strong Eclecticism of those years. In a way those brave early modernist were on similar position of the arts and crafts movement, but with a strong difference regarding the possibility of incorporating in a total manner the use of technologies in order to produce pure machine made artwork, this developed in the bauhaus, where the machine was considered just a tool.There were then even more hardcore people like Loos who even believed in the total distinction of art and craft ( with architecture belonging to the latter) or other like Behrens who had a more expressionist approach, so the panorama was quite wide. In synthesis the arts and crafts were still let's say believing in the symbolic nature of an architectural artifact, while the new objectivity guys were more for an architectural language which was per se non-representational, and for that as base was chosen classical architecture. Was this choice scientifically based? Probably not, but what is sure is that the systematic purification from any ornament became very soon quite dangerous, mainly as Adorno stated in the 60's simply because to cut it short, the absence of style became it-self style.
In practice over the years Rationalist architecture for its characteristic "economy of means" too easily was exploited by capitalistic processes, with its "cold and cruel" aesthetic, in a way betraying the initial democratic intention. Today there are still architects working with the rationalist agenda, like Lacaton and Vassal and atelier Kempe Thill, mainly in the real of social housing, achieving in my view amazing results. The former recently won a very important prize, in which the jury recognised that "The modernist hopes and dreams to improve the lives of many are reinvigorated through their work that responds to the climatic and ecological emergencies of our time, as well as social urgencies, particularly in the realm of urban housing" and more "The architects have expressed that buildings are beautiful when people feel well in them, when the light inside is beautiful and the air is pleasant, and when there is an easy flow between the interior and exterior.".
Here i am not stating that all architecture should look like that, and I agree with you that regulation ( modernist invisible hand) and algorithms are in a way leaving us with apparently a lower set of possible choices, when instead the set is much bigger. If you think for example how much robotics could be used within the modernist agenda to produce much more interesting results, when the conditions allow it. The work of Gramazio and Kohler on the robot as an artisan/co-creator it is emblematic, and it surely open more questions regarding the society in which we want to leave, regarding for example ethics and the value of subjectivity. So what i mean is that in the end it is possible to go beyond the biases that are (or we) set, and explore new possibilities.
If we start questioning deeply the built environment in which we live, we can see easily that certain biases are deeply entwined with the failures of our economic system. The inability to incorporate entropy in our system of thought, resulting in the impossibility of including negative externalities in our production system, influences any type of architecture in which we live. Probably the most inconsistent would be indeed Rationalist architecture. So in this case the question would be, how would look an architecture of true economic mean, which is able to incorporate the true impact on the environment of our production ? A possible answer is maybe in the Green Corner building by Hanne Holtrop, where the facade elements are directly casted on site in the ground, creating a wonderfully detailed facade with very minimal use of formwork.
Such complexity oriented approach, I am not sure could be feasible, if it would be possible, it would require us to think in a radically new scale, spatially and temporally. It will surely be hard, but as you stated a manifesto could really help, and maybe the time is mature enough.
Regarding your concern toward contemporary architecture, I think we should be really careful there. As demonstrated by some researches this type of critics are in some extent linked to some alt right extremist positions, which in turn could really poison the discussion. The whole nostalgia movement, with the reproposition of old scheme i think it should be watched very critically.