Historical artifact.
For me that is the ambiguous case...
"Ambiguous" was a very poor word choice. "Special-case" is more fitting. Modifying a simple data-type...
const char * p = "hello";
const uint8_t LedPin = 13;
...is a special case where const is right-associative. In all other situations, it is left-associative.
At least... const char * p = "hello"; ...Make it look like a "const char" ... pointer ... named p.
I agree. I would prefer const to always be right-associative. I think that is much more readable. (I assume it is not solely to allow for constant member functions.)
But, it isn't (except the one case). For me it's much easier to always (well, mostly) treat it as a left-associative modifier.