That would be difficult, because you need to change the structure so you are looping over a computer and collecting the fixlets, instead of looping over the fixlet and collecting the computers.
If you wanted the relevant fixlets for the computer, that would be easy -
(name of it, concatenation ", " of names of relevant fixlets whose (name of site of it = "Enterprise Security") of it) of bes computers
I’m not sure it’s efficient enough to be used at scale, but this is what I was able to come up with -
(name of item 0 of it, concatenation ", " of names of items 1 of (item 0 of it, elements of items 1 of it) whose (exists (results (item 0 of it, item 1 of it)) whose (remediated flag of it))) of (elements of item 0 of it, item 1 of it) of (set of bes computers, set of fixlets whose (fixlet flag of it) of bes sites whose (name of it = "Enterprise Security"))