I’m not sure what you mean by this. In phonetic transcription, rolled r is unambiguously [r]. In phonemic transcription… well, /r/ can be ambiguous depending on

I’m not sure what you mean by this. In phonetic transcription, rolled r is unambiguously [r]. In phonemic transcription… well, /r/ can be ambiguous depending on what language you’re transcribing, but that’s OK because phonemic transcription isn’t supposed to represent specific sounds anyway.