Mold comes from moisture.

This implies a steady hand but a gentle one.

We've brought in two dehumidifiers which are helping, but I'm not sure what the root problem is or even who to ask for help.One contractor said moisture is coming through a hole in the exterior stucco, but another said no way because the vapor barrier would block it. 1st one recommended installing insulation, but I've also read this can increase condensation problems.

There's moisture getting in somewhere -- that's what's warping the floors. 

With the sun beating down on roofs year round, or leaves falling and sitting there causing moisture to go under the roof and rot wood, the usefulness of shingle roofs is not a lot over 10 years.  

The meter will detect the presence of moisture.

I don't know if all the moisture in this photo was because the floor is soaked or if this is because they sprayed it with something.This is quite an aggressive home renovation they have done without even consulting me. 

Laminate still has wood dust in it that can warp when exposed to moisture.

Otherwise, maybe a gentle reminder that they're responsible for the lawn care - and maybe offer to install a timer so they don't have to think about it.  

But I know that when I step away from my computer and the world of gentle and well-mannered real estate investors, the real world of real estate investing is filled with land mines with incompetent and crooked investors constantly giving me advice that seems eerily similar to that I get on BP.