Since the latest installer didn't work for Mac OS High Sierra here is what I did to make it run:

1. Preparation
- Download latest Wineskin Winery
- Start Wineskin Winery and install Engine WS9Wine2.22
- Update Wineskin Winery by pressing the button "Update"

Wineskin Winery should look like in "Image1.png"

2. Create Wrapper
- Start Wineskin Winery
- Press button "Create New Blank Wrapper"
- The you set the wrapper-name in dialog (see Image2.png) and press OK
- When creating the wrapper is ready find your wrapper in /Users/<your-users-name>/Applications/Wineskin (see Image3.png)

3. Extract game folder
- Navigate in Finder to Applications/Stronghold Classic, open context menu and select "Show package contents"
- Copy Stronghold from "drive_c/Programm Files/GOG.com/Stronghold to your home directory (e.g. /Users/yourname)

4. Add Programm to Wrapper
- Open finder where your wrapper file is and open context menu and select "Show package contents" (see Image4.png - sorry, is german)
- You will see some folders and the app "Wineskin" (see Image5.png)
- Click on "Wineskin" app and select "Install software"
- At the tab "Configuration" click the button "Install Software" at the bottom
- At the next screen click the button "Copy a Folder Inside" and select the Stronghold Game you have copied prior to your home directory (e.g. /Users/yourname)
- In the next screen select the suggested Stronghold.exe
- Close application

5. Start Programm
- Click on your Wrapper /Users/<your-users-name>/Applications/Wineskin/<wrapper-name-you-set-at-beginnig>

DONE

Thank you! This worked even with Big Sur (beta) to run Stronghold Extreme HD. The only difference was that I used "WS11WineCX64Bit19.0.1-1" as the Engine running on Unofficial Wineskin Winery.