You needn't use split(). A regex is sufficient:

my $str = "foo|{baz|qux}|fax";

my @parts = $str =~ /(
                        \{.+?\}  # e.g., {baz|qux}
                     |
                        [^|]+    # e.g., foo
                     )
                     (?:\||$)    # |, or end of string
                    /xg;
$" = "\n";
print "@parts";
__END__
foo
{baz|qux}
fax
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