An on_ent_create event would be cool, too.

Well you also have to set the on_create_event somewhere, so you need some special function anyway. So why not create the entity from this function and then do all the init stuff there? The attached function (when calling ent_create) is then left for user stuff.

No, I don't want this.

But you need to set the event function somewhere (if this was possible).

Then code your function like it was an event and call it from your routine where you do ent_create. That equals to some sort of on_create_event.

I've been at that point and at the end I figured that some on_create_event does not make sense.

macros are evil.. defining macros for engine functions is super duper super evil..

ps: for an on_ent_create function.. I'm not too sure if it will work, but you could get the last object in the linked-list ( see ENTITY struct, C_LINK next). If this object has one or more follower after a frame, these objects probably have been created (I'm pretty sure the engine always inserts elements at the end.. at least this would make sense and you could give it a try).
You could accomplish the same behaviour for on_ptr_remove.

I'll give it a try. Putted it on my todo-list for a future version. Conitec time FTW!