Any particular place the z key resulted in freeze? The freeze is usually an indicator that there is some infinite loop going on, there might be some rare conditions you have that caused that. If you could send me a zipped save folder located at C:\Users\<your_user>\AppData\Roaming\WizardsOfTheCode\Soulash\saves\1 it would help me find out what's going on. If possible send it to support@wizardsofthecode.pro
The design maps are used to generate the world at new game, but during play the actual maps are inside the save folder so everything can be persistent.