"Should it be? Yes, it's 2018"- you got 100 points on that one;).
"Does it matter? Not really" - is arguable, though. It's true, one doesn't type high security info in the subtitle editor. However, to get into the editor, you have to log in, and by logging in, you're giving your e-mail and use a password, or connect through your Google account, or through FB. All ways of connecting to Viki involve some type of personal info shared with a third party, so I wouldn't exactly say "not really". To my support, my cellphone won't even let me access the subtitle editor, because of the risk I'm supposed to take by doing that. Not that I subtitle from my phone, but I was curious if the security warning disappears when logging in from another device.
Now, do I think someone will hack my account? Most likely, not. Do I believe it's important for Viki to update it's security certificate? Totally. Unless they plan a DramaFever move, aka a sudden closure, and don't bother with such trivial stuff anymore.
I'll take your advice, and definitely won't lose sleep over this; it's one of my favorite things to do, and Viki can't top that. Not in its current state, at least...:))