No, I haven't checked over large C++ code bases, but I will do this.
Btw, one fear I have with this check is that the automated fixits are somewhat risky -- unscoped vs scoped enumerations has ABI implications and changing from one to the other may break the ABI.
I am not familiar with these specific ABI implications, if you could help me with some keywords/references/link to start to investigate, I am happy to deep dive into it. I am also willing to discard the automated fixes if it makes this review better. What do you think?