Specularity looks a bit too flat to me (it looks like the wood is well polished), but heh, still very nice !
Strange you can't run realMyst, though. Since Windows 7 it's more tricky to get it working correctly, but if you get the latest patch and set compatibility to XP, it should still work. Additionally I use a no-cd patch (just for conveniency, I still have the cd), and it's fine.
But well, as you say, it might be from tweaking one of the game's file (always make backups, heh ?)
Otherwise, you could use the Myst V version of Myst, or even the Uru version. Both come from realMyst with little to no modification to the meshes (near the library it's the exact same). The library is also in the same location for both, meaning you can load the Uru version over the EoA version of the Age in Uru (wow, all this version stuff is getting confusing), which should allows you to see the closed door. The command must be something like /exec PtPageInNode("Fireplace"), from within the MystMystV Age.
Additionally, it allows you to see that the fireplace simply doesn't fit in the building