agreed with jaytea. you're thinking of the brackets in the context of your own code-- for mIRC to actually understand that "while %x < 1)" was a syntax error it would require mIRC to also know that you meant "1" and not "1)"-- and since mIRC does not expect strings inside quotes, there is no way of knowing. this is why it will only parse )'s if the condition began with a (. this is by design, and very much expected, or someone else would come here complaining, saying:
"
hey guys, while is acting weird!
while %prefix isin a. a: a) { echo -a hi }
"
Stick to the proper syntax rules defined by mIRC (dot your i's, cross your t's, and read
http://kthx.net/ftb/#34 ) and you will be fine. Playing on the edge cases of the interpreter will likely lead you into trouble.
... as for the splay thing, I agree that mIRC should mention it cannot read the file, not pretend it does not exist.