In the next release of Melodic and Noetic, bug fix imu_transformer: Fix transformation of the orientation of IMU by peci1 · Pull Request #15 · ros-perception/imu_pipeline · GitHub will be released, which fixes bugs in computation of orientation of a sensor_msgs/Imu message after applying a transform.
The bug has been there almost forever (reported 7 years ago), so it is possible some code exists that actually depends on the wrong computation. According to wiki, no officially released packages depend on imu_transformer. However, some non-published packages can. If your package does, please check whether this bug fix affects your code or not.
The main change done by the bug fix is in this diff: imu_transformer: Fix transformation of the orientation of IMU by peci1 · Pull Request #15 · ros-perception/imu_pipeline · GitHub .