Hi Paulo,
Prior to the B1 9.1, the DI API/DI Server/B1 are single thread. It is not safe at all to use multi-thread in you add-on. The main concern is that Company object is holding some static environment variable as critical section, which is not implemented as multi-thread.
However, good news, since B1 9.1 version, B1/OBServer/DI API/DI Server can support multi-threading in a safe way.Therefore, you're recommended to go for B1 9.1 instead.
Kind Regards, Yatsea