Type-changing record update ignores type families

I would like this to compile:

type family F (a :: Bool)
type instance F True = Int
type instance F False = Int

type family G (a :: Bool)
type instance G True = Int
type instance G False = Bool

data Rec a = MkR { konst :: F a
                 , change :: G a }

ch :: Rec True -> Rec False
ch r = r { change = False }

The ch function does a type-changing record update. Normally, a type-changing record update can be written only when all fields that mention the changing type variable are updated. And ch does not update konst, whose type mentions a. But it's OK, actually: because F True (old type) and F False (new type) are actually both Int, all is well. Yet GHC rejects.

Unlike some bugs I report, this one is from a Real Use Case. (I have a practical, fancy-typed library I'm building that wants to ensure that a particular record-update updates certain fields.)

While in town, should probably also fix #10856 (closed) and transitively #2595 (closed) (which, I think, is effectively a dup of #10856 (closed)).