I saw a similar post addressing this for $variable$ types.
My problem is that i am using <$set> w/ a filter to get the tiddler title based on a name passed to it, which restricts me to the <<variable>> usage.
The below macro works great if the title passed is a single word such as 'Alarmed'. the modal will pop up w/ the tiddler.
If i pass a mult-word title such as "Alarmed and Dangerous" the modal will fail.
\define modal_link(title:none)
<$set name="tit" value=$title$>
<$set name="myTid" filter='[!is[system]regexp:<tit>]'>
<$button>
<$action-sendmessage $message="tm-modal" $param=<<myTid>>/>
<<myTid>>
</$button>
</$set>
</$set>
\end
<$action-sendmessage $message="tm-modal" $param="Spell/DnD5e/Animal Friendship" /
\define modal_link(name prefix)
<$macrocall $name="render_modal_link" title="""$name$""" tidd="""$prefix$/$name$"""/>
\end
<<modal_link {{!!slot0}} "Spell/DnD5e">>