Use <br> (shift+enter) for new lines.
Do not use absolute column sizes, only percentage.
Note TCPDF doesn't handle some advanced HTML tags and some CSS.
You can enclose language strings by square brackets to be translaed, and even specify language file which have to be loaded (e.g.[com_content:Article]).
 
 
Possible replacement fields are: 
 
{order_id}
{invoice_number}
{contact}
{logo}
{start_note}
{end_note}
 
{invoice_date}
{taxable_payment_date}
{maturity_date}
{shipping_date}
{payment_type}
{variable_symbol}
{finnish_index_number}
{customer_number}
{shopper_group}
 
{items}
 
{billing_address}
{shipping_address}
 
{customer_note}
{extra_fields}
{signature}
{pagination}
 
{order_status}