Extracting values from external data files for a property in `.csproj`?

var SteamInstallPathFromRegistry = OS == "Windows_NT" ? $"{MSBuild.GetRegistryValue(@"HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Valve\Steam", "InstallPath")}" : "";
var SteamDir = OS == "Windows_NT" ? SteamInstallPathFromRegistry != "" ? $"{SteamInstallPathFromRegistry}/steamapps": "C:/Program Files (x86)/Steam/steamapps" : $"{Environment.GetEnvironmentVariable("HOME")}/.steam/steam/steamapps";

var HasteAppId = "1796470";
var Libraries = System.IO.File.ReadAllText($"{SteamDir}/libraryfolders.vdf");
var InstallLibrary = Libraries;
// var InstallLibrary = Regex.Replace(InstallLibrary, $"\"{HasteAppId}\".*", "");
//     InstallLibrary = InstallLibrary[(InstallLibrary.LastIndexOf("\"path\"") + 9)..];
//     InstallLibrary = $"{InstallLibrary[..(InstallLibrary.IndexOfAny("\r\n".ToCharArray()) - 1)]}/steamapps";
    InstallLibrary = Regex.Replace(InstallLibrary, $"\"{HasteAppId}\"(.|[\\n\\r])*", "");
    InstallLibrary = Regex.Replace(InstallLibrary, "(.|[\\n\\r])*(?=\"path\").{9}", "");
    InstallLibrary = Regex.Replace(InstallLibrary, "\"[\\r\\n](.|[\\n\\r])*", "/steamapps");
    Console.Out.Write(InstallLibrary);