Camtasia Mac recordings can probably be exported only using the program and not with some 3rd party software. There is a dedicated export function in the program that can help you with this CMREC to MP4 conversion. No other software is most likely capable of such conversion.
Convert Camtasia for Mac record file to MPEG-4 video file format.
We found one software available in the database for this conversion.
Apple macOS / Mac OS X software - convert cmrec to mp4 on OS X
Video editing tool for Apple Mac computers
Convert from cmrec file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.