That is a plate bracket made for something else, modified to work on the fiero.
I found some photos of the original bracket. The originals were unique being very deep to reach the back edge of the opening and a cup center made to fit the fiero curvature. The bracket you bought, modified to work is unusual also since most brackets available these days are not made that deep. Not perfect but at least it is being offered.
I’m guessing your bracket came with large washers to go behind the abs strips so they don’t crack and nylock nuts so it doesn’t have to be very tight yet won’t come loose. If not, you might want to go to the hardware store and buy some nylocks and fender washers or replace the abs. Nobody is going to see it isn't perfect and the holes are not so close to the edge to be a problem.
I doubt there are enough aero nose fiero owners that live where front plates are required or simply want a front plate to justify a production run on original style brackets.
One way to make these is to use 1/8x1 steel strip with a scroll bender to follow the perimeter around, then use a standard plastic tag bracket on the front and drill two holes with no welding required. You'd need an aero nose or an original bracket to get it right.