Complex sentence: If you're leaving silly messages for friends, no one is going to bat an eye, but if a reasonable person would view it as a malicious edit, the date on the calendar isn't going to save you from a block.
Split into simpler sentences: If you're leaving silly messages for friends, no one is going to bat an eye. If, however, a reasonable person would view your edits as malicious, the date on the calendar isn't going to save you from a block.