The tasks should be still visible as the siperian workflow implementation shouldn't have changed in MDM 9.7.1 (as far as I am remember).
However, the big question is why are you upgrading to MDM 9.7.1? MDM 9.7.1 is out of support since Dec 2017. Any particular reason for not upgrading to MDM 10.3?
As our other application are on MDM 9.7 and client wants to move all those in single go to the higher environments.
You will need to revert back the Workflow Manager back to Siperian in Workflow Manager workbench, as well as you need to map it as the primary workflow engine in the Workflow ORS mapping, as part of the upgrade the workflow engine is defaulted to ActiveVOS, which is the recommended workflow engine with MDM 10.
You should also plan to move to ActiveVOS as the Siperian workflow engine has been deprecated.