Making no claim to understanding tcl; what the code appears to be doing is:

1. for each row in the table;
2. query the text for each column within that row;
3. split that text on newlines;
4. find the maximum number of lines in any column within that row;
5. set the row height for that row accordingly.

SOmething roughly equivalent in Perl terms to:

my $maxRows = $tableMatrix->cget( -rows );
my $maxCols = $tableMatrix->cget( -cols );
for my $r ( 1 .. $maxRows -1 ) {
    set $maxHeight = 1;
    for my $col ( 0 .. $maxCols - 1 ) {
        my $text = $tableMatrix->getText( -row => $row, -col => $col )
+;
        my $nLines = scalar split "\n", $text;
        if( $nLines > 1 and $maxHeight < $nLines ) {
            $maxHeight = $nLines;
        }
    }
    $tableMatrix->cset( row => $row, height => $maxHeight );
}
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You'll have to work out the appropriate methods to call for what I've shown as getText() & cset().