There are basically two types of error messages in the Migration Manager logs:
1. Messages that Migration Manager code generates when it executes various processes, or encounters a problem with the normal flow of processing logic
2. Error messages returned by the local environment (local system, Exchange, IIS, DC etc) that Migration Manager software is communicating with.
When Migration Manager itself generates the messages, we always do that in English. When Migration Manage console or agents receives an error or informational message from outside, we log it as it is received according to that system's locale. This cannot be changed on our side.