My other main problem with the UA is how it gets increasingly weaker as the game goes on, assuming you don't go on a massive conquest spree (and gets way too strong if you do). Maybe that's by design, but I really feel like there are way too many pure conquest civs in the game already. Yes sure, the WLTKD piles up into infinity assuming you work your merchants and turn your writers/artists/musicians into great works (I also tended to pick merchants from any free GP event/wonder/policy) and +15% food in all cities is definitely nice, but later on even with a fairly high number of settled cities you never stack the trait food/culture high enough to feel significant, and with the way the drop-off works you seem to start off from 0 again every era. What I'm trying to say is that I think there are too many eras

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Maybe there is another solution one could employ? No drop-off but only gain yields in the capital? More yields in later eras but with even harsher drop-offs (maybe full drop-offs by design)? Maybe something else?
Either way, if the idea behind the rework was to make the UA more interesting than 'permanent WLTKD with a bonus' it might have failed to deliver on that, but then again it's quite possible I misunderstood the intention.
As for the Paper Maker, it is definitely decent enough, would it still be decent enough without the out of control growth and permanent WLTKD? Not so sure about that, but it is possible.