If the abs is malfunctioning can it affect the transmission?
It may be bad cv joints causing an abs problem and something binding up on the driveline (a cv joint or bearing). That will definitely affect the trans. Your abs is possibly malfunctioning due to the mechanical problem(bad cv or bearing, etc), thus causing the trans. to work harder to move your vehicle, due to the resistance of a failing part in the transaxle.
I would check the drive line and all moving parts. You can bring it in to any of the brake shops and they'll usually check those parts for free. At least you'll then have an idea of what may be the problem.
Search Buick Terraza Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Buick Terraza Experts