Is there any way to create a multi-column table of contents?
Not seamlessly, since most people need the exact opposite: columns after the front matter or abstract. You’ll find column settings in the Layout compile option pane for RTF (and the other word processor formats if you have the Java converters installed). Additionally Scrivener doesn’t really have a ToC feature like you might expect. You can copy and paste a static list of text from document names, using
Edit/Copy Special/, but that won’t update as you change the outline. It’s the last thing you would want to do. But adding columns after you compile is pretty easy to do in a word processor.