I just checked this issue also with Transifex support and here is the reply:
"WPML integration was built by the WPML team . We have upgraded our api to apiv3 and unfortunately the WPML team did not migrate the integration to apiv3. So the integration is no longer supported. From recent communication they do not have plans to update and support apiv3 unfortunately."
any news about an upgraded integration with Transifex?
Transifex is no longer a partner for WPML and we are recommending you choose one of the other partners from our list here https://wpml.org/translation-service/