Hrm, I tested to see what the current behavior is, and I don't see this change interfering with backwards compatibility.

When executing test_alias, the 1st line either executes the /test alias if not invoked from a channel editbox, or otherwise it tries to execute the channelname as an alias with test as the command line. The 2nd command always invokes the # alias. So, allowing # to be a comment shouldn't interfere with what scripts are doing.

Something else that's equivalent of what you're wanting to do is having REM be the 1st word of the line, where it turns that line into a REMark. I didn't find this documented, but I stumbled across it when I tried to create an alias named rem.

alias test_alias {
# test
$chr(35) test
alias # {
echo -a hashtag alias $1-