I totally understand these concerns and we have reports as well. But honestly there's no single theory that can be devised. Yes, it might be true that the bugs may have been identified over the period of time (https://wpml.org/download/wpml-multilingual-cms/?section=changelog).
Usually these cases tend to refer to some DB corruption, due to an interrupted operation (by anything like a conflicting code, connection break, caching, firewalls or etc). The custom or 3rd party plugins/themes are also a major stakeholders.
For the 3rd party code, we have a compatibility team which works closely with popular ones (or most used by WPML users) and also try to bring 'em onboard by our GoGlobal program (https://wpml.org/documentation/support/go-global-program/).
But of course, not everyone agrees and not everything is compatible.
Given that, I can suggest to consult with these WPML Developer Resources and align accordingly where it deems necessary: