I usually work directly in the project window, so I didn’t even think about the sample editor. But there it would be of course also very helpful. When I asked my question, I was thinking directly about the DOP window. We often edit old projects and mix them up to Dolby Atmos. So we work with finished stems and split them back into individual clips/events as we edit. Since a new instance is not always created, there are sometimes 10 or more DOP effects on the respective reference file. These can then never be found again in the split clips/events.
Therefore it would be really helpful if in the DOP window (and where else it is needed) the timecode would be stored.
As a first measure I will now create a new version every time, even if this is not necessary. At least then I won’t see a DOP effect on an event at the end of the project that was actually applied to an event at the beginning of the project, just because it’s the same clip.
Then my question was at least good for this insight. 
With Nuendo, this has been working since at least version 4. I’m also dealing with other DAWs and am always annoyed that I can’t simply select a range on a clip as I can in Nuendo, but always have to create/cut a new clip.