Placed in remote section, events turned on
alias cda { return cda }
alias ada { return ada }
alias cdf { echo cbf }
alias cba { return cba }

The red lines are what I entered into mirc's command line

//echo Output of CDA: $cda
Output of CDA:
//echo Output of ADA: $ada
Output of ADA: ada
Typed /cdf
//echo Output of CBA: $cba
Output of CBA: cba

It looks like $cd* is getting truncated to just $cd in mirc 6.12 (maybe 6.1x and higher) All my examples work fine in 6.0x and lower