Some possibilities:

# Assumes $search matches /^\w/ and /\w\z/.
next unless $language =~ /\b\Q$search\E\b/;
[download]

my @languages = split /,/, $language;
next unless grep $_ eq $search, @languages;
[download]

my %languages = map { $_ => 1 } split /,/, $language;
next unless $languages{$search};
[download]

By the way, $language should probably be named $languages.