Likely is because the superserver or webserver port is being used by other application... or just locked at OS level. Try to find out if there is any app using it... using the Task Manager or TCPview... if you can't find any app using those ports, change them in the cpf file using some other numbers above 60000 and restart. DO A COPY OF YOUR CPF FILE BEFORE MODIFYING IT (just in case). Other way to test if its related with used ports would be to restart your machine... and try to init Caché afterwards.

Really interesting project... would the plugin that you've built work in windows?

Very interesting exercise. Do you have any real use cases to visualize what sort of tasks IRIS would be able to accomplish with this minimum configuration?