It would be fun to create a Max app/utility for reordering or creating chains of « single cycle waveforms » and then generate a .multi file out of that. At some point I considered Max for generating random « sample chains » for the 301 but the way it handles sub-folders was not satisfying enough and immediate for that (so I ended up doing that with a very rough Lua script haha).
That being said, having the ability to visually tweak, re-order, preview the waveforms or samples in Max to make them morph/coincide together the way you want and then export this to a .multi might be quite « easily » done. I might look into it soon
I think that an envelope generator has been created by chapelierfou not so long ago, Max is probably a very good and appropriate tool to do that.