Probably somebody else already posted it - then I’m sorry.
I think it would be great if expression maps would use Midi-Note-Numbers for keyswitches AND if HALion would do the same and wouldn’t use normal notes - sometimes you are busy with software which uses other note-terminology and then it’s a bit confusing when you have to translate HALion notes to Midi-Note-Numbers.
But I guess that’s because HALion was already created in 2011 and was/is used in Cubase first.
Here’s a brief summary of why things are the way they are: https://www.steinberg.net/forums/viewtopic.php?f=246&t=129322&p=700760&hilit=scientific+pitch#p700760
We are looking at ways of making this easier in future versions.