Based on your question, I added the option to set intensity_by='row_percentages' and 'col_percentages' to cvms::plot_confusion_matrix in v1.7.0. Note that a separate intensity measure must be used for sum tiles (when add_sums=TRUE) as described in the docs.

I recommend also making future requests for cvms in an issue on GitHub, since I rarely see these stackoverflow questions: https://github.com/LudvigOlsen/cvms/issues