Magento 2 – Add Custom Attribute on Order PDF Print All Action

First of all, copying files that can just be overridden from the Core to Local is not best practise as it can possibly give you more work when upgrading Magento.

I have tested your case and found your solution:

First of all I rewrite it in my own extension:

 <models>
            <sales>
                <rewrite><order_pdf_items_invoice_default>MycompanyName_Myextensionname_Model_Order_Pdf_Items_Invoice_Default</order_pdf_items_invoice_default></rewrite>
            </sales>
 </models>

Then I override the function you mentioned above:

 $options = $this->getItemOptions();
    if ($options) {
        foreach ($options as $option) {
            if ($option['value']) {
                if (isset($option['print_value'])) {
                    $_printValue = $option['print_value'];
                } else {
                    $_printValue = strip_tags($option['value']);
                }
                $values = explode(', ', $_printValue);
                foreach ($values as $value) {
                    $lines[][] = array(
                        'text' => Mage::helper('core/string')->str_split(strip_tags($option['label'] . " - " . $value), 40, true, true),
                        'feed' => 40
                    );
                }
            }
        }
    }

What I have done here is just removed the part where you draw the label and added it to the part where you print the value.

If you have long labels/values and you want to keep it on one line, I would increase the value in str_split.

You are mixing up two different comments here. The code $invoice->getCommentsCollection() will retrieve comments entered via this box

which will appear here in the admin

The Magemaven comment is saved with the order object - see here

So something like this should do the trick:

$order = $invoice->getOrder();
$orderComment = $order->getCustomerComment()? $order->getCustomerComment() : $order->getCustomerNote();
$page->drawText($orderComment, 35, $this->y, 'UTF-8');