You might have experienced errors as below while tracing rooms and changing room properties.
These can usually be seen as notifications, rather than errors. They refer to the Room Mapping section of room properties, as below.
Energy Simulator assigns pre-loaded room types based on the category of room you chose. Based on that, the room mapping facility (more information detailed in this article here) specifies building types and room types. (Note if you by default trace CIBSE room types, ASHRAE standard rooms are meant to be unspecified as shown).
More specifically, it is the Part L 2021 room types that are the root of the notification.
Part L 2021 calculations will work fine even if you do not define building and room types here, as the software will consider Part L 2013 data and assign it automatically. Likewise, heat load calculations also would stay unaffected due to this errors/warnings.
However, if you need to select a new room type that is only available in Part L 2021, you may assign one as required.