Ben, I'm not sure what you mean by "ck spelling" but when people know better than to use an obscene word, they sometimes substitute the equivalent word in a foreign language, thinking that makes it ok, the same way as we more often see the use of the first letter followed by "word" (as in "the X-word" where X is one of several other letters and everyone knows what word is really meant when that phrase is used). To my mind, a substitution intended to impart the same meaning without uttering the wash-your-mouth-out-with-soap word is no different than saying what you really mean. If the word has been used often in your experience, causing you to consider that it has been assimilated into English then even when you change the spelling by adding a "c" in the middle of the word still does not change the fact that it is an obscene word in another language and the English translation of the foreign word is equally obscene.
Personally, I spent my career providing engineering support to military and intelligence agencies and my vocabulary was considerably widened by long association with Navy chiefs, who are very deserving of their reputation for colorful language. Although in informal settings, I often use words that are considered unacceptable in normal circumstances, I am capable of censoring my speech and writing when those words are inappropriate or likely to offend some people. I am certain that the obscene English word for feces is not acceptable to be used here and, especially since WikiTree is an international community, I do not think that obscene words in foreign languages are any more acceptable, irrespective of whether you think they have been assimilated into English.