Have you used Unity? Since this is c#, I imagine a lot of Unity developers would be able to jump onboard for small projects if you could find a way to let them attach .cs scripts to entities via Hammer/Jackhammer, just the workflow that exists with GameObjects in Unity's editor.
Mockup of an entities tab in JACK (point/brush based):
editor with entities list
right click on entity to create script for this one gameobject that inherits the entity classUnfortunately J.A.C.K is closed source as far as I know, otherwise the UI part of this idea would have be really easy to implement.
(edit: just found out about Sledge, cool! So that's an option)
Bad example with the Bool MyTouch function since everything after calling base() would not execute cause it returns a value, but you get the point.
