translate5 supports the openTM2 xliff.
Word count
translate5 uses the word count information contained in openTM2 xliff to provide the word count of the project, if the word count is not submitted manually on import time.
Track changes
Changes can be tagged in openTM2 xliff in the export using HTML syntax (be careful: this is not useful inside openTM2 and may break it. It is only for use on file level).