Sure, you can do that if you can absolutely guarantee that everyone will always respect that separation and there will never be ambiguity between your internal and some partner's representation – even during incidents, even during low-level CSV-to-DB ETLs during incidents ("just one time, I promise, we don't have time to build the proper adapter, but look how similar their and our formats are").

In places where it matters the fines are so high, that everyone are stickler to the rules. It's like a hot oven - not merely a warning of risk. It's actual risk which was touched and which burned.

If an adapter would put your yearly salary at risk (not an exaggeration) would you quicken it?