If I provide a wiki page when creating the event, it's not separated by newline or paragraph from the description when I display the event. It's caused by Markdown consuming newlines (unfortunately) unless there are more of them or there are some spaces at the end of the line.

In the example screenshot, "fullday" was a description.

I also wonder whether it makes sense to provide a separate field for a wiki page link, when it's not shown somehow separately in the event display, but simply added to the description. For this approach a separate field is not necessary, the event author can simply paste the link into to description himself/herself.