Try it without <haxelib name="swf" /> in the project.xml, and see if that works. We recently merged SWF support into OpenFL (core) and have made improvements to deeply integrate it
I believe that MovieClips should work, but you cannot use code added to the timeline.
However, you can use the undocumented movieClip.addFrameScript function (which mind you, has a zero-based index) to attach Haxe scripts to frames on a MovieClip
The ID will be called “library” by default (though you could add id="puppy", etc, to change this name)
You can now load the whole timeline, or a symbol that was marked as “Export for ActionScript” in Flash Professional / Adobe Animate.
var timeline = Assets.getMovieClip ("library:");
...
var clip = Assets.getMovieClip ("library:MyExportedSymbolName");
If you use generate="true", classes are generated for your “Export for ActionScript” symbols, letting you instantiate them directly, similar to what you would use in ActionScript:
var clip = new MyExportedSymbolName ();
You can add prefix="SWF" (or some other prefix) if the exported names will conflict with other classes you have in your project. With the latest OpenFL, you should also be able to use custom base classes in your SWF, and have it link up for you, similar to ActionScript