Can you simply ask them to walk through their submission line by line with you, explaining what it's doing?
This. Code reviews, especially with junior devs, should always be done as a conversation. It's an opportunity to learn (from both sides), not just a a bunch of "bad implementation. rewrite" thrown in the PR.
Our wedding was under 5k, excluding dress and suit. Immediate family and close friends only, less than 40 people. Major expenses were the photographer, food and booze. We rented a cheap, small place in the countryside, we planned and did everything else ourselves, having a kanban board in the kitchen for a year was fun! My wife even did the cakes herself because she's an amazing amateur pastry chef. No DJ, but I spent months on and off curating a playlist with a good flow and steadily increasing intensity.
It was the perfect wedding. Huge amount of work but 100% worth it.