It looks like that both .motn and .cdr files are used by Apple Final Cut Pro and as such, this software is the likely choice for this conversion. That is, if its even useful or possible to do it. Probably used for burning compilation of motion files, or something like that.
Convert Apple Motion motion data to Apple Final Cut Pro CD or DVD master image file.
We have found one software suitable in our database for this conversion.
Apple macOS / Mac OS X software - convert motn to cdr on OS X
Final Cut Pro is non-linear QuickTime compatible video editing software developed by Apple, Inc. for Mac OS X. The last version called Final Cut Pro X was completely rewritten and it is heavily based on Apple iMovie. It supports various video formats including DV, HDV, P2 MXF (DVCProHD), XDCAM (via plug-in), 2K, 4K and 5K film formats.
Convert from motn file
to cdr file
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.