sprintf needs clarification

[Altai-man]

https://design.perl6.org/S32/Str.html#sprintf says about "mostly identical". "Mostly" is how much exactly, is it absolutely equal to all things that come below? Judging by the current implementation, we don't have side modifiers like %ll and they aren't planned either.
But they were described in the docs by some reason. So the main question here is: are size modifiers like %ll and others planned or will they never be implemented?
For the original reasoning see Raku/doc#870 (comment)