I would translate «grass matt» by «tapis floqué» in French, even though it is generally made of paper and not tissue or cloth. It is used for model train scenery.
Great fort, and great use of System X parts. How many basic sets did you use ?
The only thing I would add is a kind of stables for drought horses, on the right part of the fort, with an attached corral. Blacksmith and «cantina» could also add to the atmosphere…
Mine is made up entirely of the old fort system parts, more versatile (but more fragile…).