I think it can (I recall reading about a hinter, and I may have used on in another one or two of my repos) but it really is two-sided. That 'lines of code in repo' classification should probably be C or C++ for Rcpp as that is how the package is built: it contains a boatload of C++ code, and less R code.

Also not that the 'tag' (under 'manage topics') does have 'r' as well as 'c-plus-plus'. So I'd be inclined to leave it as is.

Then again your search argument has merit...

Yes I used what is described here to exclude parts of repos from the count. That doesn't apply here. Not sure if there is an overall override.