Where possible I have made comments about the code itself, but given the size of the code base in osmplotr I was unfortunately not able to spend too much time digging into the specifics.
I feel this could be a frequent challenge: reviewing a large package may be too much to expect of reviewers (Jeff mentions that his review took 10 hours).
I previously suggested, based on Mozilla’s experience, that we try to limit the size of reviews. I said 400 lines of code before. This might be too little. But perhaps we could try to encourage authors to submit packages for “first” review at some early stage when they have some core functionality built, even if they don’t think the package is feature-complete. This would have the additional benefit of getting authors on board with various best practices, tests, CI, etc. that have benefit during package development.
At the very least we could warn that the longer the package, the longer it will take to review! I suppose I could take a look at the previous review times and see what the relationship is.