The triple brace notation indicates that the filter inside the braces will be evaluated. BUT, they don't get evaluated if they are in strings. Which yours are. So in each of yours, the {{{ and }}} get evaluated as if they were tiddler names.
More to the point, you don't use triple brace notation within filters -- you don't need them.
Only the 2nd filter is correct. The 4th filter is not only incorrect because of the triple braces, it is incorrect because it is missing a left square bracket in front of "enlist".
I think you're trying to count the number of tabs. I guess the way to do this would be to give each tab tiddler a tag, like "mytab".
Then your tab macro would look like
<<tabs "[tag[mytab]]" "[[recall]]" "$:/state/tab/deck">>
and you could count the tabs like
<$count filter="[tag[mytab]]" />