Someone reached to me about supporting this type of texture atlas. Not sure what the name is but it is stated as "Texture Atlas" on the Adobe help pages.

It seems that the there are one sheet image, which has components of the sprite (instead of framed) and two data files, one is for defining the components, and one is for the animation. Implementation would be quite complicated as each frames frame would need to be rebuilt with the components and the placements.

References

• Dot-Stuff/flxanimate
  • flxanimate/FlxAnimate.hx
  • ...and some other files...
• Gamua/Starling-Extension-Adobe-Animate
  • src/starling/extensions/animate/AnimationAtlas.as (pay attention on the aliases)
  • ...and some other files...
• https://helpx.adobe.com/animate/using/create-sprite-sheet.html
• https://creativecloud.adobe.com/en-US/learn/animate/web/export-sprite-sheet

Sample files

spritemap.zip