The only crash I have seen with Keyboard Maestro in High Sierra is caused be broken Color Pickers.
You can launch Keyboard Maestro editor with the Shift key down which I believe stops the Color Pickers from loading. Search your system for old color pickers and remove them.
Known problematic ones include:
- RCWebColorPicker
- WebPicker (might be the same as RCWebColorPicker).
If you find others that are incompatible, please add them to this topic.