Alright. Sorry for the delay. Had a main sewer line leak into my crawlspace over the weekend, so that took priority (sigh, it never ends...).
So, here are photos of my property showing the affected area (it's an extension with a separate crawlspace.
Photo 1 shows the terraced garden and the affected part of the house (2 floors). There is just loose paving on the floor, which should be easy to lift up if I need a trench or re-grading here.
Photo 2 shows another angle of the same area in photo 1.
Photo 3 shows the side pathway. The crawlspace entrance leads to the affected area. The saltillo tile is on a concrete substrate. The grading is not so good and water tends to puddle in low points as you can see from the efflorescence. I've been told drains can be put in by cutting a strip through the concrete.