Something that stands out right off the bat is you want to loop over the keys not the entire hash, like so...

for my $key(keys %HoL) {
  &{$HoL{$key}[0]};
}
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Also, you cannot embed subs inside strings without resorting to trickery, so instead you can one of the following ...

    print "$key -> ", &{$HoL{$key}->{$i}}, "\n";
    print "$key -> @{[ &{$HoL{$key}->{$i}} ]}\n"; # voodoo!
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    --k.