If you wrote a program, you would know that asymetric callbacks are messages that arrive in a message queue like an external email, and you have to process who the sender was and all contexts. There's a lot that goes into writing a scripting engine. mIRC is 21+ years old, not an object oriented project, not a dot-net project, everything is hand sewn.

Well. At least I won lunch.
Good philosophy, see good in bad, I like!