Legacy Feature
As of SAP2000 V11.0.5, all temperature loads are incremental, so the conversion should be C:F = 5:9.
We removed the 32 deg conversion with Incident 11547 in Version 11.0.5, and Reference Temperature was removed with Version 11.0.0. Note that Material Temperature affects material properties and it is not the same as Reference Temperature, which no longer exists. Material temperature has no affect on the loads.
To understand why we dropped the reference temperature, try to figure out what happens when you assign temperature load to some elements and not others, and how to handle multiple additive temperature loads to the same element. We used to have rules for this but they were too complicated. The new approach is simple to understand.