5.3 does have the ability to show CC during recorded show playback. (Of course, the program has to have closed captioning - so prime time shows are good to test).
For my 5.4 test I would turn on CC, see that I had it on the live show, turn on the timeshift, and the CC would stop displaying. I also tried a similar test on a station. I verified CC was working, pressed record, let it record about 30 seconds or so. Immediately when I had pressed record, the CC stopped. When I stopped the recording, CC resumed. The playback of the recorded snippet also did not have CC.