Although that quote was about the C# code itself, it is indeed because I never took the effort to support it and nobody asked for it until now.
Is there a reason why you need to use 32-bit? I guess there are still too many people with old computers out there who are using it, but I would think almost anyone who would be interested in running new software would have a 64-bit pc.
Although there is no technical limitation for 32-bit, you will have to change a few files to get it working because I hardcoded the x64 value to keep things simple.
You will have to start by checking out the TGUI.Net project with git (i.e. "git clone
https://github.com/texus/TGUI.Net").
Open extlibs/build.bat and change the 3 occurrences of "vcvars64.bat" to "vcvars32.bat". There are also 3 occurrences of "x64" in that file, leave the "...Tools.x86.x64" on top alone, but change the ones in the cmake and msbuild lines to "x86".
Go back to the root folder and open build/TGUI.Net.sln with a text editor. Replace all occurrences of "x64" with "x86".
That should be enough to get 32-bit working. If you update the submodules and run the build.bat file in the build directory as described in the readme then it should build 32-bit libraries (this will take several minutes). Let me know if it works or not. If it works then I'll try to come up with a way to let you choose 32 or 64 bit without having to change the scripts manually.