I just downloaded the latest Microsoft RTF specification. It unzipped into a doc file.My version of WP9 crashes when trying to open this file, although Wordpad opens it immediately.
But a "Save as" of the file from Wordpad in RTF format opens correctly in WP9. It would seem that it is not the basic Wordperfect program that is the problem, but instead the third party import conversion utility that still doesn't cut it.
And, of course, Microsoft is quite adept in exploiting any flaws in a competitor's conversion utility.