The only way to achieve "tmb to mmsw conversion" is to use the Movie Magic Screenwriter software from which both .tmb and .mmsw files originate. This procedure is basically a recovery of documents (.mmsw) from timed backups (.tmb), which is probably done through some recovery function.
Convert Movie Magic Screenwriter document timed backup to Movie Magic Screenwriter document.
We found one software available in the database for this conversion.
Microsoft Windows software - convert tmb to mmsw on Windows
Program used to write screenplays
Convert from tmb 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.