The way the game works right now, if you want to mod it just for you own race (and not all kingdom/empire) You pretty much have to copy all the old buildings, and techs. Change the techs to offer the new copied version of the building, then change the copied building to use the new tiles.

Edit: I said it kinda backwards, but I think you know what I mean (you have to make the copied building require the copied techs).

You need to look at TechTree_Trog and Techs_Trog (or Techs_Amarian depending on faction allegiance). Look for these files in the Only-SP folder. Then most of the buildings are in EmpireSpecialImprovements for empire, yada yada. Look in the Core Improvements folder. The improvements are spread out amongst a few different xmls, but they are all in that folder. What I did to make my race have completely different improvements was to take the original starting buildings (I used empire, so labor pit, archivists, etc) and prereq them to the race of fallen. (All empire factions have been set to the fallen race). Make sure in your raceconfig file that you have the <RaceClassification> set to your race name. I think there's another file you have to edit for that as well. I believe it's Racetypes. If you want, check out my wip mod here:

https://forums.elementalgame.com/394286

I'll be uploading an update later, as I had to fix the spells since 1.08 came out.

At least if you check all that out, you can get an idea of what I did.

What is the actual code in your xml? Did you copy the whole thing? This is an example:

<?xml version="1.0" encoding="iso-8859-1"?>
<ImprovementTypes>
 <DataChecksum NoParse="1">
  <Ignore>DisplayName</Ignore>
  <Translate>DisplayName</Translate>
 </DataChecksum>

<ImprovementType InternalName="F_Hovel">
  <Prereq>
   <Type>Race</Type>
   <Attribute>Fallen</Attribute>
  </Prereq>
 </ImprovementType>

</ImprovementTypes>

That should do it. F_Hovel is already defined elsewhere, all you need to do is assign one more prereq like above. Things get weird if you start overwriting stuff thats already there. Plus this is a lot cleaner. That's how I have it in my files, and things work fine. I can build the hovel as any other empire, but can't build it for my custom race.

Ooh, looks good. Seems a bit more like some desert civilization with that color scheme though, heheh.