Just to give you a little advice- If you need information from Steinberg, you probably need to contact Steinberg directly. This is a user forum and isn’t specifically monitored by Steinberg. If any users can help you with your issue, they probably will, but I have come to the conclusion that a lot of my own issues with Cubase are not things typically experienced by other users, since I rarely get any satisfactory feedback on the forum. It’s likely that your issues are not things that other users have trouble with, or it is something easily found in the manual, hence the lack of response.
That being said, I myself have only GA4SE, so I do not have the Acoustic Agent that allows me to set up a cymbal choke. If you have Acoustic Agent in GA4, I believe you can create a choke, but I’m not certain of that. I was able to do it when I had a trial version of GA5, but I have not yet made the full purchase, so I can’t look at that specifically at the moment. But it’s in the manual.