You should probably change

my $count = scalar keys %{ $doc };
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to

my $count = scalar @{ $doc->{$sub1} };
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And similarly for your other counts.

Update: no, your other counts are fine. And you don't need the scalar as you are assigning to a scalar, so you can do as you have done for the other counts:

my $count = @{ $doc->{$sub1} };
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