Some users might use Smartcat in some projects to benefit from the collaboration features or because their translation team does not have access to another tool like SDL Trados, but they would still like to maintain some Trados TM up to date for projects where they cannot use Smartcat or because their customers is requesting that format back.
There are 2 possible cases:
If they use Smartcat to translate files created with Trados (.sdlxliff or .ttx), once these files have been translated, they can be exported back to that format and using the Trados batch process, can be used to update the TM.
If they are translating documents other than the formats listed above, it is possible to export industry standard TMX files at the project or document level and import these files in the Trados TM. These files can be exported at any time during the project so the external TM databases can be updated in real time.