You are right - section columns are still not supported, and I fully understand your concerns, but the feature was postponed up until now.
The public item is migrated to our feedback portal here:
RadRichTextBox: Introduce support for layouting the text in a section in multiple columns
I would suggest you to vote for the item and subscribe to it to follow its development.
This feature is among the top twenty requests for the WPF suite, so we are currently conducting initial research which will determine the effort needed for its implementation. Once we are ready with the it, we will consider planning the feature for one of the following releases.
That said, we still cannot commit to specific timeframe at this moment, but this definitely came back to our sight recently.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items