Hi Jakub,
there have been a few crash fixes recently (i.e. since April when you posted this message), see for example notes 2197473 and 2229311.
So first I would recommend to retry with the latest patch level. If the problem persists, you definitely should open an OSS ticket under BC-MID-RFC-SDK. Crashes are serious problems, which need to be investigated by the development team. In the course of an OSS ticket we can provide you with debug versions of the DLLs to get better stack traces and dump files with symbol information, or we can perhaps even debug into it here at SAP, if you can reproduce the crash in a test program that we can run over here.
Best Regards, Ulrich Schmidt