r v5.40 pre 12 x64 win 8.1
use instance: copying project B's tempo envelope into project A in order to make a live set containing several songs.
1: do above
2: end song1 in project A with a "gradual" tempo change marker.
3: paste project B's tempo envelope into project A at time X after gradual tempo change marker from step 2.
4: issue: your tempo data is not pasted at edit cursor at the designated time position. see gif
the envelope paste event happens quick and moves me several minutes further in the timeline so watch out for that in the gif, it makes the behavior a bit difficult to see when it exactly happens.