"Guests aren't going into walkthrough enclosures!"

Because of how the game works, guests won't be attracted to walkthrough exhibits without incentive to come inside (animals alone won't cut it, guests are unable to view animals they share a space with from paths). In tandem with the newly-added guest gates and exhibit paths, you should also put viewing aids like benches and viewing canopies, as well as things like amenities to further coax the guests into coming inside.

"Certain things aren't showing up!" or "Things aren't working properly!"

Odds are that you have other mods installed that are conflicting with Folksy Facelift. Zoo Tycoon 2: Folksy Facelift was designed solely as a patch for the vanilla game in mind and edits a lot of things, so if you have it installed alongside other mods that change just about anything in the vanilla game (especially when those things involve animal changes, new maps or UI or lang changes), odds are that lots of clashing will occur. Not every mod will war with Folksy Facelift, mind; I've heard that Artifex's mods (Arabian Nights and Island Excursions) don't clash with it too much, and personally speaking, having Thom's Cheat Codes mod installed during development really helped things along.

Zoo Tycoon 2 mods work in a sort of hierarchy system - sorted by name, the further a mod is down the list of files, the more priority it has when the game loads up. With most mods, the most common way to negate this is to add lots of Z's to the front of a file - e.g. changing the name of "MyMod.z2f" to "zzzzzzMyMod.z2f". This fix should work fine with manual installs but may cause issues if you installed Folksy Facelift with the installer (like not updating properly or fully uninstalling) necessitating manual removal of the main .z2f. If you have used the installer to download Folksy Facelift and would like to use the Z trick with it, make sure you remove all of the z's before updating or uninstalling it.