> Go through all changes, understand what changed and how it solves the problem.

GP has said that they can't do this, since they're unfamiliar with the language and that specific part of the codebase. Their best bet AIUI is (1) ask the AI agent to reverse engineer the diff into a high-level plan that they are qualified to evaluate and revise, if feasible, so that they can take ownership of it and make it part of the feature request, and (2) attach the AI-generated code diff to the feature req as a mere convenience, labeling it very clearly as completely unrevised AI slop that simply appears to address the problem.

Not being familiar with a part of a codebase is not an incurable condition.

If the conclusion you made of that there is no workaround, then let that be the entire point. The alternatives are to get over yourself and ask people to implement a feature, or to understand how to help and then help.

The former is what OP did; the latter I described what I see as an efficient way of achieving while making use of an LLM-produced PR.