use 5.010;

use strict;
use warnings;

while (<DATA>) {
    chomp;

    say "$_ ",
        /(<+)[^<>]*(>+)(*COMMIT)(?(?{length($1) == length($2)})|(*FAIL
+))/
        ? "matches" : "does not match";
}


__DATA__
<1>
<<2>>
<<3>
<<<<4>>
<<5>>>>
[download]

Output:

<1> matches
<<2>> matches
<<3> does not match
<<<<4>> does not match
<<5>>>> does not match
[download]