Tai-tri, US 852, Sudachi, one of the Yuzu seedlings, both the Bloomsweet in a container and the Bloomsweet in the ground, are all just beginning to put out some new leaflet grow.
And a surprise, a pomelo seedling that was left outside in a container on the patio over the winter is also beginning to show a little bit of new leaflet growth, although the old leaves do not look so well, very pale and yellow. I believe the seed had come from a Reinking pomelo (though I can't be absolutely completely certain that that was the specific pomelo variety).
Looking closely, I'm barely seeing some tiny new leaflet growth just beginning to start on the Changsha, but that's planted in warm south-facing spot, with a brick wall behind it.
The leaves on the Changsha have begun greening up more, becoming less yellowish in hue.
The Ichang papedas (smaller in size, one on its own roots, one grafted) and the Ichangquat seedling (own root) still do not look any different from how they looked at the start of March, though the stems still look a relatively healthy green color.
April 29, 2020 , climate zone 8a, Pacific Northwest
update May 1, The Ichang papeda that is grafted, the one that did not look so well, is now just sending out growth of many small leaflets. The other smaller Ichang papeda on its own roots has been slowly greening up and looks healthy enough like it could begin sending out new leaflet growth at any time.
If you look at the before and after pictures, even on the Bloomsweet, you can see how the leaves look a noticeably greener hue now than they did at the end of winter, indicating the plants kept their leaves through the winter, the leaves are still alive, and have at least some ability to recover. (It's not a huge color change, but is noticeable) It's the same on my cold hardy gardenias, although the extent of the color change on the citrus is a little less. At least for the gardenias, I read that's an indicator that the roots may not be able to draw up as much iron due to the low temperatures. I don't know whether that same thing could be true of the citrus.
For reference comparison, I have a Satsuma seedling growing in a container right next to various other hardy citrus seedlings, left outside over the winter on the porch, and the leaves on the Satsuma are looking really borderline about whether they will be able to stay on the plant without falling off or recover; they will probably drop.