Hi,
As you understand, we can't help you on the warning which are not related to HikaShop ; so we can't help you for the the system "languagefilter" or the "viewlegacy" parts.
About the email, as you see it is the "order_status_notification.html.modified" ; which mean that you have modified the email.
And because there is no more PHP in the official HikaShop "order_status_notification.html" mail ; I think that you have inserted the PHP yourself.
So it won't be possible for us to give you an answer for some code we do not know or we did not wrote.
My recommendation is to not use PHP in the "html" part but just HTML and tags.
You can put some PHP in the "preload" part of the email ; it will be easier for the organisation and you will be able to access to much more elements.
About the tags, you can have content tags (to display something) but there is also conditional tags ( if ) ; you can see some example in the email with the IF for the product code.
I think it will be easier to put an IF in order to display or not the addresses and set the variable used in the IF in the email preload.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.