It is a false positive by itself, ...
That was to assume ... and that was only one of the problem fields (even if I maybe had stated on that a bit too strongly).
... but in general, FileRep detections only work On-Execute and not On-Access.
Is that really intended? If that is the case, FileRep might be really questionable, as not only avast is "looking inside archives" (and installers usually are "packed to archives"), but FileRep is mostly a "lookup in a big database" (and not avoiding "trying to do something unallowed during runtime"); see also
here the description of the FileRep-functioning. And a "lookup-protection" should work on any access (and not on execute), but it seems obvious that a "behaviour-protection" (that would prevent unallowed operations) can only be reacting on execute.