Unrelated to the issue of using
% symbol in layer names, but related to exporting to JSON file in general: something else I have learned is that the
length of layer names has an effect on how long it takes to export a scene to JSON file with all the PNG sequences separated in individual folders. The shorter the layer name, the faster the export. Longer layer names increase the time it takes to export. This should have been something I understood intuitively because it is logical that the more data the computer has to process and write to the file, the longer it takes. But I didn't notice it until recently because on some of the scenes I've been working with recently I included some "descriptive" info as part of a layer name, such as: 'Paul's Shadow on TOP of car roof 24' (the 24 referring to the layer opacity of 24% , so the shadow is transparent on top of the car roof) Because by default JSON layer structure assigns the name of the layer to each PNG image exported, a lengthy descriptive layer name like 'Paul's Shadow on TOP of car roof 24' increases the time it takes to export each image. Better if I had named the layer 'Paul Shad Top 24' or 'PShad Top 24' or 'PShad24'.

- Screen Shot 2022-12-22 at 10.43.29 AM.png (70.1 KiB) Viewed 8139 times
The fastest way is to name layers simply with an
A, B, C, D, E, F, G ... system , so a layer may simply be named 'A' , or a
1, 2, 3, 4, 5, 6, 7 ... system so a layer name is just '1' or at most '1-A' .
I believe that the JSON naming structure can also be adjusted to not include the full layer name , but in my laziness I have left it set to the default naming structure which includes the full layer name appended to each image.
----
Speaking of shadows (or other layers with the
opacity set to other than 100%) , I would suggest that you always double-check the layer opacity after the layers have been imported into After Effects because I have noticed that After Effects tends to change the opacity one percentage point up or down. So if you had a layer set to 24% opacity in TVPaint , when you check it in AE it will likely be set to 23% or 25% . In most cases the difference between a layer's opacity being 24% or 25% is not going to be noticeable, but still ... if you set it to 24% , it should stay 24%, not change to 23% or 25%. I don't know if this is a bug in TVPaint's AE Export/Import script or a bug in how AE reads the script.