That letter can even state that they owe additional if they caused a lot of damage that the deposit didn't cover.

It sounds like the weight of the island is adding load to the joists in the floor causing the slope.

Are you a fantastic tenant who laways pays your rent on time and causes zero problems? 

However, the new ADU laws in California that went into effect Jan 1 2020 may provide a loophole.As I understand the laws, they say that the city cannot use lot coverage to prevent you from building an ADU under certain circumstances, therefore I wonder if I could do the following:STEP #1: Convert two garages into uncovered carports, causing them to be removed from the lot coverage and bringing our lot coverage well below 45%.

https://www.nfpa.org/Public-Education/Fire-causes-and-risks/Behavioral-risks/Hoarding?

That I think would be better cause after renovating and getting new tenants I'll sell the property within 1-2 years and in those 1-2 years I would like to get 35-40% of my money back that I've invested in the property plus the profit from selling.

I think that if the structural issues are so severe as to possibly cause collapse, and were cited as early as November, there was no good reason other than convenience to have them complete their lease term through end of May anyway.

More in the systems rather than cosmetic, cause cosmetic is easy and can be done partially.

I didn't see any chipping paint, asbestos ceiling tiles falling down (ceilings are sheet rock) or 9x9 flooring tiles in poor condition that would cause anyone harm.

They sound difficult and could try to cause you other problems.