Hi,
Many 1970s releases have credits like this: “remixed by … at …”
I use “mixer” and “mixed at” instead of remixer, … because they created the original mix. I suppose that’s correct, but I like to have confirmation before I change “remixers” on other releases.
For example (Release “Twin House (Guitar Duos)” by Larry Coryell & Philip Catherine - MusicBrainz):
I’d say you have to know the history of the recording. If this is indeed the first mix ever of this recording than yes, mixer, would actually be better than re-mixer. If it’s a new mix, not a remix of the original mix, than mixer. If they took an existing mix and mixed it from that, than it’s remixer. So, I think you are right on this.
I have now 4 1970s albums in a row with “remix” credits on the original release. They consistently use “remix” for mixing the original recording.