Files with tmb suffix can be found as exchange files in Translation Memory eXchange format used for translation Memory data.
TMB file extension - TMX editor user file
What is tmb file? How to open tmb files?
File type specification:
File extension tmb is mainly related to TMX (Translation Memory eXchange), a vendor-neutral open XML standard for the exchange of Translation Memory (TM) data created by Computer Aided Translation (CAT) and localization tools. The purpose of TMX is to allow easier exchange of translation memory data between tools and/or translation vendors with little or no loss of critical data during the process. In existence since 1998, TMX is a certifiable standard format. TMX is developed and maintained by OSCAR (Open Standards for Container/Content Allowing Re-use), a LISA Special Interest Group.