This was almost two days ago, but... So I got the next problem report from OS, where he attached a sample document which had a table at the beginning. The document text was exported but no the table structure. (So if you had at least one line of text before the table, the bug was not there, that's how I did not notice it.) The one-liner fix is now in the CWS and it's backported to ooo-build master as usual.
During the week I got some feedback from Oliver Specht on my GSoC work. I decided to dedicate a whole day to address those issues (these were all regressions compared to the old RTF exporter). Here are the results:
One remaining question is that he mentioned something is problematic with the table of contents export, but I could not reproduce the bug so far.