There are multiple AI issues caused by the movement AI failing to hold orientation.
The AI is amplifying oscillations it develops in order to use transverse thrusters for forward thrust. This ship provides a good example since it's particularly small, has slightly off center mass distribution, and has a laser pointer to make the oscillations clear:
The same issue can occur with the Ion Frigate, but it's less automatic. Turning off the transverse thrusters reduces the problem, but the movement AI should not be thrusting forward or backwards in ways that will produce torque, using transverse thrusters only for deliberate turning or strafing.
The AI also turns its sides to the enemy in order to attempt flanks unless its movement direction is already perpendicular to its attack orientation. It "thinks" it's doing so safely out of range, but it's inevitably taking a chord that goes closer to the enemy, potentially a lot closer, and turning usually impairs its ability to hold the range open. The AI should only turn in combat as a result of a deliberate decision to present a different facing to the enemy, not as a consequence of a movement order.
Prioritizing translation is mostly needed to correct maneuvering errors which the AI couldn't identify anyways, and should never happen without explicit player command. This might result in impaired mobility for already crippled AI ships, but what the AI does in a hopeless situation is less important that what it does with still functional ships. Humans can recognize and try to correct for mistakes. The AI can't and needs to avoid as much as possible taking actions that might be mistakes.
