In case someone else comes to this thread - using *.aseprite file importer seems to be the way for now. It’s fairly easy to port the importer from MetaSprite to C++ or any other language, it’s pretty well written. I went with the similar way, using group “@points” in which every layer specifies single point (sprite pivot, hand locations, etc). Just use cel’s position.
Also, in case you need it, every cel is compressed using zlib, if you want to use “uncompress” function you’ll have to include 4 byte header and footer with hash, skipped in MetaSprite.