I am running 8.54, and have been doing CISPR15 tests with a LISN and TEM cell. I made my own custom projects with minor adjustments which were copies of the relevant .prj files under the src folder.
I had a go at customising my own segment files, but couldn't quite understand how they worked. They are all text files, but I think the structure requires some understanding of the code.
What version are you running? I see there is a new 9.18 release.
In your version, is there a TC folder under src\CISPR 32_EN55036_V1_3 folder? In 8.54 are TC folders under CISPR 14, 15, & 25
FYI, when I have contacted Tekbox support they have always been very helpful.