Okay, I am glad, I don't need to answer this request. First of all I am a non-native English speaker.
For me it's hard to get your main point, there is little structure in your request and a lot of anger. I can understand but most of the time it doesn't help to vent that much.
Change your text a bit. Don't start with the dissatisfaction, put it at the end.
Put the matters in order:
1. Is it not possible to respond on requests in a more timely manner 1-3 days at max.?
2.Can't support of contributors be improved?
For an ambitious company like Rakuten Viki I would expect a better service ...
I would always chose a request to be more like a formal letter and less than a indifferent social media comment. At the end it's only a human sitting there at the other end, you don't have the CEO there to read it. Try a calmer version. And be precise about your questions, don't distract with comparing to others or your sentiments.
Hope it helps!^^