FSX.cfg file doesn't have anything to do with Zurich installation. It's SCENERY.cfg that perhaps has a problem.
If you already had Zurich before (perhaps, manually added to the Scenery Library), even with the error, the scenery will work the same, because probably the error apparently happens in the first stage of scenery.cfg parsing, when installer tries to find if you already have an entry for Zurich, in order not to create a double one.
Can you please send it to me via email ? If you fix it yourself, we'll never get the chance to add another special case to it, and make the installer as bullet-proof as possible.