While this forum (and myself) mainly uses SMBX2, I think I might be able to help a bit:
Before I start, I'll be referring to the 1.4.X series as SMBX38A, as it is a completely separate, incompatible engine to what Legacy SMBX (1.3) and SMBX2 uses, so many of the bugs will be completely separated. The name comes from the developer's username.
I googled the error code and it appears to be the result of some DLLs being missing, What's most likely is that you are missing a component that SMBX38A wants. Since it happened on both times you attempted to use two separate versions, it can't be that one of the downloads was corrupted. Try putting your SMBX38A folder on your desktop. Try running it as an administrator (right click and click run as administrator) to see if that fixes the error. Also make sure that you have the latest version of the .NET framework installed. Since SMBX38A uses the VB6, have you updated the runtime to the latest version?
Also, there's a dedicated 38A forum at the Wohlsoft forums where you probably won't be shouted at for using your version. The 1.4 stuff is also referred to as SMBX38A (or 38A for short) They should probably know WAY more than me, and it would be a great idea to ask on there if none of my solutions work. Find it here:
https://wohlsoft.ru/forum/. The 38A stuff can be found at the subforum labeled "Super Mario Bros. X by 38A (SMBX-38A)"
If in doubt, I'm pretty sure that you can use PGE with the 1.4.X series. It's generally a better editor and you probably(?) won't need to do those. You'll need to download a configuration pack, however, and I don't know whether testing works. Once again, I don't really use SMBX38A so I might have gotten something wrong.