The terms and language are different! But why exclude costume/historical dramas? I mean, unless you only want to understand modern day dramas, otherwise don't you want to learn all the cool complicated terms they use in ancient times? It's more arcane and almost not used in modern times (except sometimes to poke fun) but really fun! Plus you get to learn nice complicated vocab and more about the history and culture!
Also, while I agree that they need to check the quality of the subtitles but it's a MASSIVE amount of work to go back and ensure the all the translations are accurate. You're editing so you should know how much effort it takes to listen to a segment, check its meaning is accurate, think whether this is the best way to phrase it for the casual viewer AND the language learner (both of who have different viewing requirements and you need to strike a balance between them both), check the grammar, etc. There's a few hundred shows out there, with 20-30 1-hour episodes on average, and even if we just limit it to Chinese-English translations, it's a Herculean job.
Assume that it's only 100 shows * 20 1-hour episodes each = 2,000 hours of watch time
Depending on the quality of the original subtitles, I take anywhere between 3 hours to 8 hours to fully edit a show. Maybe I'm slow, who knows? Editing is a pain in the ass.
Let's assume the quality is top-notch, and it just takes 3 hours, that's 6,000 hours of editing or 250 days of non-stop editing or 750 normal (8 hour) working days or slightly less than three years of working days.
How many bilingual people does Viki have to hire to complete all that work for just those 100 shows?
Yes, it'd be absolutely wonderful if Viki could do that, but are you learning or are you being spoon fed? The Learn Mode has a dictionary there, and you can click on the word to refer to the dictionary, if you're still going to be misled by wrong English subtitles, then you're obviously not learning. And if you realise the subtitles are wrong, all the better, that means you're learning.
Sorry if this sounds harsh, but language learning is a rough journey.