I think in general adding more hard taxa to the CV makes it better, because it forces it to learn more sophisticated rules. It can also help reduce potential cases where the CV is currently far more confident than it should be, because it is unaware of the third possibility.
For example, in this T. x glauca observation, the CV reports 98.5% confidence (combined_score) for the observation to be T. angustifolia, but it shouldn’t. I surveyed the CV scores for maybe 20, and in many if not most of the T. x glauca observations I checked with the CV, the CV incorrectly had >~90% confidence for one of the two species. Reducing such unfounded confidence would inherently improve accuracy.
For a true cryptic hybrid where it is 100% impossible to tell them apart from a single phot, I think humans maybe will also be unable to do them in most cases, so the performance is not worse than, and possibly better than, the status quo.,