Do the days to maturity in the Transplantation chart include the time in the nursery?

No, and that keeps your nursery on time: in Transplantation, the Average DTM counts from the day you plant in the field. The weeks in trays go in Days in nursery, which come before.

When you plan a transplant, Heirloom adds the days to maturity to your Field planting date to give the First harvest, and counts back the Days in nursery to give the Nursery start date. Before you copy a number from a seed catalog, check whether it counts from seeding or from transplanting.

The steps are in How Charts work and Add a planting.