Bug with "regionally in" or in Index?

In 6.11 “A Word About In” in the manual, it describes the “regionally in” test. if the croquet box is regionally in the mystery value, ... where “the mystery value” is an object that varies. But the Standard Rules defines The verb to be regionally in implies the reversed regional-containment relation. The Standard Rules do NOT define that relation. How it is defined is a mystery to me. But in the Relations section of the Index’s Phrasebook, the regional-containment relation is defined as room-to-room, which seems wrong. Why isn’t it region-to-room or room-to-region? Or even object-to-something?

Is this a bug?

It looks like an index bug; the relation should be shows as “region to room”.

Hm. Maybe it’s deeper than that. I’m getting weird errors with

The RRR is a relation that varies.
… now RRR is the regional-containment relation.

I submitted a cosmetic bug. We’ll let wiser heads figure it out.