Some of the things people say...leave me shaking my head...the retaining wall needs to be replaced to stop the ground from shifting???? Whoever told you this, don't take any more advice from them.
There is often a distinct pattern to a series of cracks which sometimes suggests the cause. Therefore, evaluating a house with various cracks is best done by someone who can examine them on site.
I can tell you a few things. Cracks in the retaining wall likely have nothing to do with cracks in the house. The farther the wall is from the house, the more this will be true. Brick veneer is supposed to be supported directly by the foundation, so it is unlikely that its weight has caused any cracks. Maybe that was some more of that "advice" you got.
To comment any further, we would need to know a lot more about the cracks you observed. How wide are they? Exactly where are they located? Are the walls made of wallboard, or are they plaster? How long are they? What are their directions? It won't be possible to monitor them over a period of time (months) because you don't own the house, but that should be done also to fully evaluate the cracks.
Architect (NY) and Home Designer (PA)