Bit-wise oring is your friend. Although the answer comes out lower-cased :( - unless I change those pesky spaces to '@'s - which I just did.

my $string ="EICHENBAUMSCHULE";
my @query = qw(EIC BAUM UMS CHU LE);

my $matchline = '@' x length $string;

for $match(@query) {
    my $spacer = index $string, $match;
    $matchline |= (('@' x $spacer) . $match) if $spacer > -1;
}

print for sort { length($b) <=> length($a) } $matchline =~ /[^@]+/g;
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