Yeah, I know, maybe most of you will find this post useless because you don't use Linux as your operating system, however, there might be (at least I hope) someone who uses IMVULite on Linux and probably experienced the same problem as me and might find my post helpful.
The problem encountered was due to this error:
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 12 (X_ConfigureWindow)
and some other ID error codes
I tried looking for some solutions online, but found nothing that could help me solve the problem, until I had the intuition that it might be useful to install DirectX on Wine, although I had never had the need to do it, so I tried installing some DirectX runtimes (maybe even more than those needed, since to be on the safe side I installed from version 11 backwards to 9) through a tool called Winetricks.
Unfortunately, having a 32-bit prefix (a prefix, or rather, a wineprefix is a way of assigning different paths to possibly keep programs installed via wine in a separate environment - Wineprefixes) I ran into problems when installing DirectX runtimes, so I had to delete the old 32-bit prefix altogether and create a 64-bit prefix.
Once the new prefix was created, I looked for a solution to avoid installing different versions of DirectX runtimes unnecessarily and, fortunately, I found the suitable solution in the dxvk project (easily installed via the Winetricks tool).
Now IMVULite starts up without errors, I might even venture to set the 3D render to Direct3D accelerated graphics, but for now I prefer to keep the render set to standard graphics as I always did.