We do not know about any possible conversion for .camthtr and .camproj files, except that they both originate from Camtasia Studio. If you are particularly interested in conversion of Camtasia files, perhaps contacting the support of the software's developer would be the wisest thing to do.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.