Valid phrases for Approve in NAC

As I understand, NAC is not programmed to accept additional valid phrases that map to "Approve" outcome in flexi task express approval (similar to Nintex 2013 and O365). I suppose you could create a custom outcome for each common response (e.g. Approved, ok, yes, etc), but that would significantly expand our 9 branch state machine workflow. Are there other options or is valid phrases on the roadmap for NAC?