I have been able to fix the problem of file attachments with quotes (') in the name by opening the ntf forum file in Domino Designer and in the Views->WebBoardSub, the last object called Untitled (Column), you will find a line like this:
Attachments := @If(@Attachments=0 ; "" ; @Implode(@AttachmentNames +"#" +@Text(@Round(@AttachmentLengths/1000));""));
Just add the following line after it:
Attachments:=@ReplaceSubstring(Attachments;"'";"\'");
And it works! (at least for me)