The Transifex integration with Bitbucket does not add default reviewers when creating a PR. This is an additional operation in Transifex. See below for docs:
Thank you for taking the time to share your feedback with us.
I will forward your request to our product team for further evaluation.
Of course, we will keep you posted on any further developments
Thank you for looking into this. Can I get an ETA on this, it would help me to plan my work.
I will probably be able to share more information about this by the end of the next week.
I will keep you posted.
Thank you very much for your patience.