Yeah, I agree with the wiggle room concept. Since I always despised the Roddenberry/Schnaubelt feud (and I do believe that the people who inserted those things in the movie knew exactly what they were doing), I personally keep all of the latter's work firmly in my head-canon (the anchor point, actually). Predominantly because if it were only a couple of ship registries from a tiny part of FJ's work, that could be explained as a one-off kind of thing, but we also have pictures of other Tech Manual pages and Enterprise Blueprints being shown on the screens when the V'Ger probe starts hacking into Enterprise's computer. They go by so quickly, it's hard to tell if it showed the other FJ ktbashes and Trek Core doesn't show them all (I honestly can't remember what was shown). The newly-remastered TMP is up on Paramount+ now. I think I'm going to give it a look to see what's there.