>>> Sorry, I don't understand what problem you're trying to solve.
>>> Why are you separating copyright text and license text?  

I don’t know how to keep the @ifinfo trick (see the attachment) without
separating them.  Maybe the @ifinfo part should be removed.

>>> Can you send me the whole file (beginning of it, anyway)?
>>> The diff is hard to read.

Attached.

>> And yeah, there could be a single macro since the two always go
>> together.

> Why is a macro needed at all?
> (vs. just using text inside @copying).

In the document, nearly the same (more on that later) copyright notice
is repeated three times.  A new contributor would have to adjust each
notice, which is error-prone.

Now, I said “nearly” because the “Copyright” lines are different, but
they should be identical.