+25% Yields from Great Person Improvements during "We Love the Empress Day" in a City. The creation of Great Works begins "We Love the Empress Day" in all Cities. Duration scales with the number of owned Cities.
Artists slot in the Paper Maker.
As I see it, the UA is shouting Tradition. If you take Progress or Authority you'll miss several GP, as large civs are usually unhappy and that doesn't work well with working many specialists. Going Tradition, capital has many specialist slots, specialists are cheaper and GPTI yield 1 extra food, IIRC. But in my experience, when going full GP, I end up working just a few (4-6) food tiles in each city. Even Academies are ignored in favor of food tiles (mostly Towns, Holy Sites and fish). You can opt for just growing for a time, but then you get less GP, and if you keep working specialists and your empire small, the city doesn't grow as much as its happiness might allow.
Also, tiding WLTED with Great Works is pushing China towards a cultural victory, as GW become more important. The Artist slot is pushing in the same direction. And, as we said before, +25% only works for yields greater than 3, so in practice that's an extra couple of yields in 4-6 tiles in some cities, at most. Hotels can multiply the tourism on those extra culture yields, so I see it even more geared towards culture victories.
If you insist on theming China around GP (which can be thematic, but I don't really know too many great people from this country, other than Confucio and Lao Tse), I'd suggest to change that +25% to yields for a flat +2 food (growth without food is not that useful), WLTED or not (WLTED synergizes with food already, so no need to make it work only during that event). The main reason for not working those GPTI is the lack of food for smaller civs and the lack of happiness to run specialists for larger civs.
When going wide, having some GPTI should help with unhappiness, though, as the city yields will improve significantly. With a focus on GP, most unhappiness will come from specialists. Paper Maker can help here reducing unhappiness from all specialist (specialists produce half unhappiness in the city, for example).
Another idea for reducing unhappiness from the Paper Maker is to yield +1/2 GP Point for each GPTI (Paper Maker yields +2 Great Scientist Points for every Academia worked in the city, same for Towns, Factories and Holy Sites), so cities won't need to work specialists slots to have a few more scientists, merchants and architects. This can be a counter for the focus on creating Great Works, not railing the civ towards a culture victory.
If that's too powerful, make GPTI bonus just +1 food at any time. Half of the city yields will come from extra pop size, anyway.