Thanks, that clears it up better.
It may be just my age, but I half-hope you don't "clean these things up" in the ways you describe. OGC Touching sounds intuitive, in its own way, but I can't immediately think of a use for it. Whereas I use current Manifold Adjacent all the time. I suppose to reproduce that with OGC tests, we would need to use Touching, but first ensure that both objects were lines or points, converting areas to boundaries as necessary (and adding a new index). Well, that would be OK, but is there a good reason to make a new gap to be filled? Is OGC compliance the only attraction?
Also, on this basis, an area object would not touch itself, which would take get some getting used to. (And it would now intersect itself.)
Breaking changes happen, of course, but it's worth noting that wholesale semantic changes like this would mean that anyone wanting to reuse old code would need to maintain knowledge of both sets of definitions, the old and the new, as well as the date and version of the changes. Translation would be tricky at times and a probable source of error.
Especially perhaps between users--think for example of all the existing spatial code on the forum. Changing the semantics would render much of this code useless, or confusing (requiring endless re-explanation) or worse, a source of error, usually obvious but sometimes subtle.
So yes, I half-hope you don't make those changes.
(Now, someone coming fresh to Manifold from, say, PostGIS, might well say the opposite.)
One way around most of this (at least a mitigation) would be to ensure that no function names were retained or reused after the new semantics.
(You could even retain both sets of semantics, replacing the "Geom" prefix for current functions with "OGC" for the new ones. I'm not sure that would be wise, it would need some thought!)