I am still having issues with this. I even tried deleting all of the overrides and I still do not get any text accompanyed with completed orders when I use certain checkouts. For example, I had a payment method set as "Check on Delivery" However, I changed the title of this payment method in the back-end so it displays as "Quote..." when I check out the text associated with this payment method in the language file does not appear on the invoice. I finally got language debugging to work, I guess by deleting the overrides and receive the following errors:
JROOT/language/en-GB/en-GB.tpl_jm_consilium.ini : error(s) in line(s) 0, 3, 22, 28, 31, 43, 49, 84, 101, 110, 117, 130, 145
JROOT/language/en-GB/en-GB.mod_jm_pagetitle.ini : error(s) in line(s) 0
Is en-GB.tpl_jm_consilium.ini the language file we edit in Configuration->languages?