The Dension connects on the external CD changer and the spec of this has not changed since around the year 2000. It is not text capable.
Your internal CD player is text capable and it will also play MP3's.
It works in the DIS because DENSION intercept the CAN bus messages of TRACK 1, TRACK 2 etc that the radio puts out to the DIS and injects it's own messages onto the CAN bus and into the DIS. So the DENSION is able to display information in the DIS while the radio is saying TRACK 1, TRACK 2 etc. It is impossible for DENSION to modify the information displayed in the radio.