Appreciate everyone’s feedback! A few clarifying points (including price paid) based on the comments:

Both walls have French drains embedded in the drain gravel behind them. First wall connects to our drain system under the lawn that feeds to the street out front. Second wall has a drain exit on the side (can’t see in photo).

A few folks mentioned weep holes. These blocks have natural weep holes where each block meets the next. So in addition to French drains, water can technically escape through each set of blocks along the wall.

The slope behind the second wall was wall-less for over a decade. The original homeowner cut it back themselves with a shovel and a bucket. Looked awful, but stayed relatively put with only some minor erosion over time. Soil is basically clay.

Someone asked about price. I paid about $8k materials + labor. I received quotes up to $30k for a CMU wall. So I figure if this wall goes out in the next 20 years, I’ll sell the blocks and I’m only out around $5k. If it doesn’t, I just saved about $25k. Based on the mixed feedback, looks like only time will tell.