display name is exactly right. The AN esp edits the cells to "Behave as exterior" and simply redirects the static mesh interiors from the default \architecture folder to our custom \allnatural\architecture folder. To create our special AN static meshes we (I) open the mesh, add a NiAlpha node to the window block in the .nif and change the texture path to a custom transparent window texture.
So as display name says, ANY mod that uses vanilla static mesh interiors, such as Cheydinhal, Chorrol, ect interiors, will have those redirected to use the AN transparent window meshes. We did this precisely so other modders could easily make their mods AN compatible.
Right. That's what I thought AN did. Which, in practice, allows my mod to only change cells that have been "modified" by AN - because those static interior meshes now have a NIF path of \allnatural\architecture\ instead of simply \architecture\. Which means that the mod will only work for those meshes that have been changed by AN, etc, etc.
The issue arises when mod authors don't use the interior meshes *as intended*. For instance, Bethesda's DLC takes a pirate ship interior that should realistically have windows but they place it underground as part of a hideout. With AN installed you'll get transparent windows even though technically there shouldn't be...one way to solve this is to make Thieves Den use a custom static that's a copy of the vanilla original.
Ok, that makes sense.
Basically what this boils down to in my head is that I'll have to add exceptions for Thieves Den and Mehrune's Razor DLC at the very worst and maybe buy Thieves Den / Mehrune's Razor and see what my mod even does in a case like this.
The real problem, of course, is that there is no real way to tell if an interior is meant to be on the ground, above the ground, or in the air. A good number of interior cells are located at 0, 0, 0 units, which tells us nothing about their location relative to the outside exterior. And even if it did, I've seen vanilla ground floor cells with 0, 0, 500 units, which would tell us that the cell is 500 units in the air, when it is clearly not.