There is a sealant we use called NP1 that does not crack with heat.

Or maybe a "sealant" like paint product to be applied to the cheaper drywall that some will choose to use to midigate its effects and still keep that drywall cheaper overall than the other options.The last question that I believe I posed was not from the previous viewpoint but was that in hearing about the metals (copper, wiring, ect.) that was affected and corroded I had not heard anything said about the metal in the nails used to connect the wood together.

There’s a lot of evidence that proves they knew about the issue...the carpet in only the living room was changed out...concrete sealant on the patio (the other side of the living room wall) as well as some studs that were replaced from the water damage.

I am painting the outside of my home in a few months anyway so I figured I may as well paint the bottom part of the building's concrete foundation with a water sealant masonry paint. 

The interior sealants don't do much of anything so the only long term remedy would be to dig out and re-seal, which of course would cost a lot and neither the turnkey company nor I would be willing to do that.The "turnkey" company has said they will extend the gutters away from the home and bring in some dirt to help slope the ground away from the house. 

@Mason Jeffries, look into adding a second layer of drywall to the ceiling with a layer of acoustic sealant between the old and new.

@Daniel SuarezAdding just sealant is a band-aid; not a permanent solution.

*Adding high efficiency water heater & furnace so we didn't have a chase in the kitchen *Custom bar and hand crafted bar top in the basement - we could have gone with something pre-made or not have done a bar down there at all - just a cool feature we added cause it added value/storage to the space  *Upgraded plank flooring in the basement - it had a water proof sealant and was about $2+ more per sq foot than the cheaper stuff *Demoed walls that would have closed off the kitchen - requiring electrical movement *Added a sprinkler system/new sod - we had a sewer pipe we replaced in the yard, so instead of just patching up what we had to, we made the backyard brand new Again, we did make a profit so in no way was this a sour deal for us, just added a lot of really unique personal touches as well as going the extra mile in certain areas.  

Several coats of primer, two coats of color and 4 coats of sealant. 

There's only a matter of time before water is going to escape through the cracks left by the drywall (or sheetrock not sure as I'm no contractor) in the top unit redamaging the ceiling on the downstairs unit but if those missing tiles were added with the sealant filling the cracks, such as the rest of the bathroom, it would fix the problem.Chime in if you will.