Office 2019 with Outlook is in 64 Bit, and Domino is also in 64 bit. However, HTMO is still using a connector from 2010 technology at 32 bit. This would explain why Outlook crashes randomly at times.
The MAPI library that HCL are using is from office 10 and currently not upgraded to a higher version. There is no alternative to use a higher version and also MAPI library support is not available.