RosettaNet rightly decided to stay in the public process space, and left the implementation of the internal private process up to the trading partners. As long as the partners can collaborate in the public process space with standardized transport packaging and routing mechanisms, to send and receive standardized messages, with un-ambiguous content in a specified choreography - the private process space of the business partner is out of scope for RosettaNet. In a sense, the public process specifications enable a dialogue between partners, conversations like "I would like to purchase 5000 units of product X by such and such date", "great, we can do that". Once this conversation has been enabled in an un-ambiguous manner that "machines" can "understand", then RosettaNet does not care if a business partner is using simplistic spreadsheets internally or sophisticated BPM (Business Process Management) solutions.
Since the de-coupling of processes from applications exists in the private space of an organization, and since RosettaNet has never really advocated how organizations should implement capability internally, the impression that RosettaNet has struggled with what user companies do in the private process space is not accurate.
Some reading material:
RosettaNet ROI studies http://tinyurl.com/yetx
White Papers on automation and collaboration using RosettaNet http://tinyurl.com/yeux