We volunteers have discussed this at length.
See this thread
Part of this one:
and also this one:
The fact is that nowadays the original translation into English is not done by Viki volunteers but by professional subtitlers paid by Viki. Because of the need to have the translation as quickly as possible. We only get to edit them.
Now, most of us (not all) will tend to edit exaggerated swear words. Maybe you have been watching episodes as soon as the translation came out, therefore before the editing? But, again, some of us are also not that careful to match the level of cursing to what it is in the original.