[Blue Skies (Jacquie)]

I don't think there are any different terms. I've certainly never heard of any difference, the track has always been straight. All the photos/images of any transit in the past (and I've seen a few Mercury transit ones as well) are always straight. That's why you can't find the term you think exists. I know you're frustrated by not being able to find an explanation for your results but I don't think it lies with the motion of the planets.

P.S. On reflection, what I would do is rather than try and get a verbal kind of response - since it's not been successful so far for you - is to immerse yourself in as much literature on transits and eclipses that you can lay you hands on. Include historical observations, celestial mechanics (as in how eclipses/transits come about) and other photos. Become the expert yourself. Hopefully along the way you'll find the answer you're looking for. It will be a journey as important as the destination.