You can be the one to make such a guide
In general, it's not going to be amazingly useful -- most people dont know anything about MQ2 scripting. However, it would be good to have here in this forum for the people that do.
A few of those you mention are not right, for example..
/return would read:
/return <text> --> return <text>
There's absolutely no difference, except for not having a slash.
/declare --> DeclareVariable -- as with MQ2, you can use short names to mean the same thing. /dec in MQ2 will do /declare, the same as Dec in LavishScript will do DeclareVariable (and so will Declare)
AddTrigger doesnt use variable names. The syntax of the match text is almost exactly the same as MQ2, it's Blech. The differences are # is @, and | is %. Additionally, whatever is in the @xxx@ with LS is ignored, it simply makes one parameter to the sub for each @@, as well as the entire line for the first param.
As far as EQ-specific commands like /face, /doortarget, etc, all you're going to be doing is removing the slash for the most part. That stuff would be found in the ISXEQ wiki on ISMods, rather than in the IS or LS wiki portions on lavishsoft.com.
Also, your info on /delay isnt entirely accurate, the ${<expression>} would just be <expression>, absolutely no different from If.
/alias has no direct translation. Alias is a LavishScript command, and you would have to use EQExecute with it in order to alias a normal EQ command (but of course, not for an IS command).
A lot of things will be like that, where there is no direct translation, but instead one or more similar methods. Or there's some cases where there is a direct translation, but other methods that may be easier are available. VarSet and VarCalc for example are nearly deprecated by data type methods. VarCalc X ${X}+1 is simplified into "X:Inc" -- that is a valid command for an int variable, or it can also be used in a data sequence like ..
while "${X:Inc}<=10". Or X:Set[360+${Math.Sin[12]}] is effectively VarCalc X 360+${Math.Sin[12]}.
