I tried again after checking my settings and it still doesn't work. I think I see what is going on (after looking at the .trarc). If you give a nickname to a built in memory location, for example c0="bit0" and r0="real0", the exported .trarc stores these as c0 and r0. If you create a user memory block and trend values from the user memory block, it exports the name of the memory block element into the .trarc. These named memory block elements are what I remember being imported from other projects with correct names.
When importing "Trend Archive into New Project...", c0 and r0 get imported but there is no link between those memory locations and the nicknames because the nicknames aren't imported along with the trend. In the case of DST0, this is a system memory location and has the nickname built into the system, so it knows that the nickname of DST0 is $ScanCounter.