As you've got no answer, I'll try to help you: the short answer is no.
(Disclaimer: I'm only a workflow-plugin observer, not a developer, and what follows is my own views)
The long answer is: the code has been designed at core to be extensible. So I suppose implemented a TOSCA-compliant parser should still be feasible.
But IMO, not sure users will be asking for it. If so, then it's unlikely to be implemented soon (but as it's OSS, one company could certainly contribute it if there's customer demand).
HTH