>I am not surprised by the following:
>coldsafety = set("safety")
>set safety &coldsafety && Working
>set safety (coldsafety) && NOT Working
>set safety eval("coldsafety") && NOT Working
>
>
>However, I am surprised by:
>colddate = set("date")
>set date &colddate && Working as usuall
>set date (colddate) && WOKING!!!
>set date eval("colddate") && WOKING!!!
>
>
>What are going on here?

I have a guess.

set safety is a command that takes no arguments! Actually, there is no SET SAFETY command! There is a "SET SAFETY OFF" command and a "SET SAFETY ON" command. So literal string substitution works, but trying to use a run-time calculated value causes a syntax error.

set date is a command that takes a single argument. That argument may be a constant (a macro evaluates to a string constant, so it's OK) or it may be a run-time evaluated variable.

In other words, the general syntax for SET commands is not a good example of language design. But hey, nobody's perfect.