While Dorico can import Cubase expression maps, getting them to work is a challenge. In every case I have had to delete the expression map and re-enter exactly what was there before and that works. About the mapping of the expression maps to the playing playback techniques I have defined every playback technique. Even if these named playing playback techniques are named exactly the same as in the imported expression map, they will not sound until the expression map is deleted and re-entered. Dorico has quite a lot of playback playing techniques defined but I don’t use any of them as I just don’t know how they connect up to an expression map.
You shouldn’t have to delete anything from the expression map after importing it. It seems as if perhaps the issue is that you don’t have the appropriate playing techniques in your project to trigger the switches in the expression map, perhaps.
My problems with expression maps were found to be solely due to importing from Cubase. Some of these imported maps caused the VSTs to not sound at all, let alone that the keyswitches would not work under any conditions. The solution is to delete the imported expression maps and re-enter them in Dorico–these work as expected. If I kept up with this forum I would have been on top of this a lot sooner.