We made many changes to the language file and am upgrading from 2.7.11a to 2.7.13. Can I overwrite the new language file with the previous version to keep my changes or were there changes to the new upgrade file?
Yes there are changes, but no worries. All new changes are always added to the END of the language file and commented to say what version it was added in. So save your modified language file... then take the new one, copy the NEW language tags from the end, paste them to the end of your old file... and then use the newly updated old file