Did you find it worked reasonably well on any portion of the codebase you could throw at it? For example, if I recall correctly, all of MajorMUD's data file interactions used the embedded Btrieve library which was popular at the time. For that type of specialized low-level library, I'm curious how much effort it would take to get readable code.
I actually sidestepped the annoying btrieve problem by exporting the data using a go binary [0] and I write it to a sqlite instance with raw byte arrays (blobs). btreive is weird because it has a dll but also a a service to interact with the files.
P.s. I have spent a lot of hours on this mainly to learn actual LLM capabilities that have improved a huge amount in the last year.