After trying to build, receiving compiler errors from Third Party javascript file that weren't there before

I have a Unity project that was working find on my relatively new machine until I tried to Build it. Not only did the Build fail, the editor is not letting me test the game because the Third Part Terrain Composer script, Map_tc.js, has numerous compiler errors, like the one below:

Assets/Third_Party/TerrainComposer/Editor/Map_tc.js(1148,77): BCE0019: ‘inputRaw’ is not a member of ‘preimage_edit_class’.

Originally, I was getting this error in Visual Studio to retarget my .NET framework to the Unity Player

The reference assemblies for framework “.NETFramework,Version=v4.6.1” were not found. To resolve this, install the SDK or Targeting Pack for this framework version or retarget your application to a version of the framework for which you have the SDK or Targeting Pack installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used in place of reference assemblies. Therefore your assembly may not be correctly targeted for the framework you intend. INFEWS_CWEB_GAME.Plugins.Player

I have since retargeted these assemblies and do not receive the error anymore in Visual Studio but I am still getting the same errors in Unity. I have checked the .NET Framework I am running which is currently 4.7. I reset the Player Settings in case I changed any while I was trying to build. I also reinstalled both Unity and Visual Studio and am still getting the same error. When I delete the file, the game runs but certain parts do not work which I assume are related to the script I deleted. If anyone has any idea why this might be happening, I would much appreciate the help.

I’m not certain I fully understand the problems, and I’m on an older version, but in case this is helpful…

I’m not sure if Unity has upgrade their runtimes/compiler, but I don’t think you can retarget to a different .NET than what Unity initially sets your Visual Studio project to, and still get things to build. That is, I think you’re limited to what Unity sets your dependencies and assembly targets to, which I think roughly translated to .net 3.5 (Unity doesn’t use the openly distributed versions of .NET, they have their own “special” version). If this is relevant for your issues, you may want to try creating a new, empty project in Unity and then seeing what the build settings are Visual Studio, and then copying those settings back to your project that won’t compile.