It seems a great tool! Delighted to be surprised.
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I do not know a free tool in this specific (but important) niche. Perhaps
Synfig Studio. On the other hand
Spine (apparenty a very similar tool) is a commercial competitor. I was considering use
Blender for Sprite Animation...
I missed the cross-platform and open source but it is enough fair I think . It seems ambitious.
Basis and
Tiled can be on the same level in the 2D Toolset.
I recommend you a intense campaign of diffusion. This project deserves
more visibility. It would be interesting that you subtitled your video of presentation.
Sorry for my creepy English.
DJuego