However, it seems more and more tenants are breaking leases and then I must make the effort to find new tenants.

You have to do this anyway so this is no extra effort

It takes time and effort to find the deals you are looking for.  

Thus, if I know your property is worth $50,000, it would always be illegal for me as an agent to instead find you a $30,000 buyer without making a good faith effort to sell at or near fair market value.

I would suggest flipping that a little and going back to the contractor and breaking up the effort.

If you are going to the effort of changing floor plan and window openings, my suggestion would be to move the front door to where the awning window is in the first pic.

My analysis however does not take into consideration the effect of an unforseen global shock or tragic event which could shake all markets, but that is the case at all times regardless of what the last ten years have looked like. 

If they refuse to fix the tile then you have to hire somebody else to fix it then decide if you want to try and go after them for any cost difference which will likely not be worth the effort as it will be difficult to prove who said what and less you have everything in writing and signed off by both parties.The way to avoid this in the future is to let the sub contractor supply the material and or make sure you have a detail submittal signed by both parties of what goes where and make sure everyone knows not to install any tile until either you or someone on your team can be on site before the tile goes down to make sure everything is in the right place. 

I would recommend against using a threaded fitting, because it would mean that you could have to successfully remove whatever fitting was previously threaded ... it will be faster and less hassle (in my opinion) to cut the pipe where you want to and de-burr it, and add the compression fitting.In all honesty, if you plan it out correctly, it won't take much effort to simply replace all the galvanized pipe in the house, starting right at the meter.  

Yes, the effects will be major and global (beyond what we are seeing with supply shortages as a result of COVID) but we haven't seen one yet...