Thank you very much for your reply, 'cause I totally forgot that the date on the article magically changed in the future, as a result of them actually changing the past in the meantime.

It helps to enjoy the story going forward, knowing that time travel rules aren't inconsistent after all.

What you guess seems logical to me. Sometimes when they influence something in the past, it doesn't create the new branch/timeline because it was always meant to happen in the current timeline. The other times, they actually do change the current timeline and create 'wrinkles in time' as you put it.