We had a similar issue. So here is what we did in our campaign : we just made sure to select a hero portrait and class of the same Archetype in the app to act as a substitute. The only time the app actually referred to a specific hero (thus naming the substitute) was with those rare Peril Effects. The app never referred to any specific Heroic Feat or to any specific value (for characteristics or attributes). But I agree it would be nice to have all the heroes from the conversion kit available in the app. I am pretty sure that if Varikas appears in the few next "Hero and Monster Collection" expansions, the app will be updated accordingly.