No. This is not about word choice.
Confusion comes from a reader’s feeling that in Kotlin, in addition to a “property”, we have some separate “field” thing that is “backing” the property… Whereas in fact there is no such thing, and the spec actually talks about “memory backed instance of a property value…”
There is no problem in “field identifier” used by the Kotlin language (like “this” or “it”).
I think not many people read or try to understand specs as deep as we do in this thread. 
Personally I’m not surprised at all that some thing in the spec, that seemed OK for years, actually needs correction.
Moreover, I can think that in the early Kotlin days no one was surprised with “Java things” appearing in the Kotlin spec, so readers understood references to some “backing field” as references to “Java specified field thing” (or as references to a “field” thing in another familiar language).