There are many buildings with systems reaching the end of their life - Galvanized hot water risers, leaking vent stacks, aging window systems, outdated elevator and fire safety equipment.

The tenant threatens to get lawyers, my concern is their safety, but I can’t get any justification to make improvements to the property for security.

Home inspectors look for safety.  

•Safety and Growth: McAllen, for instance, has been ranked among the top 5 safest cities in the U.S. since 2020.

Lastly, I don't know what your long term plans are, but having a house to return to in the States if your international adventures don't work as planned can be a good safety net for you!

I would also say that markets like Manhattan are not super representative of most markets in the US - a lot of foreign investment I'd imagine in NYC, Miami etc - I'd guess a lot of these cash purchases are more about exchanging unstable or risky foreign assets/currencies for perceived stability/safety of US top metro residential real estateI think in a lot of other markets where this isn't relevant - I think most are cash offers being "king" as not having appraisal or other contingencies that might sabotage the sale after 30 days or so and make people re-list (sellers will take less to avoid this risk and downside)

The primary benefit of a smaller  renovation is you'll have a larger safety net if the renovation gets out of hand, the property won't sell, or if it takes longer than expected to rent.

It also took me down the rabbit hole of the safety of escrow deposits which seems quite frightening.

I'm only seeing one rule (safety). 

I will under no circumstances take responsibility for the safety of a tradesmen if there are pets on the property.2.