> It’s not like programming languages support representing 61-second minutes anyway

Raku supports leap seconds. see https://docs.raku.org/type/Instant

I also like how Raku has extended this with the Q operator, allowing one to specify what should be interpolated (scalars, escape sequences, closures, etc) also with arbitrary delimiters --

   Q/I got $5 \sigh /   # literal
   Q:s/Hello $name/     # just scalars
   Q:b/hello world\n/   # just backslash escape sequences

https://docs.raku.org/syntax/Q

That may be a good candidate of something to port back when Perl 7 gets to the stage of adding new features.

In the example, the effects of "use Jolly" are restricted to the enclosing scope, e.g.

  use lib <.>; 
  { use Jolly;
    # inner scope
  }
  # TODO: this does not throw an error

I don’t have a problem with that. It can still be hard if you also want to “use Holly;” which wants some incompatible syntax hack, but at least it is lexically contained. I think the main reason this stuff tends to work out ok is that it’s so rare (in practice there aren’t enough Holly’s and Jolly’s in play so you don’t ever need to use both in the same scope).