Take a look at this characters and their number of appearances for example - https://www.tvmaze.com/shows/18175/jonny-quest-the-real-adventures/characters
Let's focus on main cast since the problem lies there because main cast can exist without being attached to any episode and in that case it will count as 1 appearance (see Bandit main cast, the character doesn't appear in any episode, should say 0 appearances).
Furthermore, when main cast character is represented by multiple actors, each actor counts as one appearance.
See Jonny Quest character for example, it says 5 appearances, but it shows only 4 episodes. That's because one actor appears under 4 episodes and another actor under 0, but it still country another actor as an appearance.
This will all end up looking correctly once I'm done watching both seasons and attache each character accordingly (since season 1 and 2 have different actors for main cast).
But there are many shows where we have attached main cast, sometimes with multiple actors for same characters, and each actor will count as 1 appearance even if the character isn't attached to any episode.
Main cast on their own should not be counted as appearances when they are not selected under any single episode.
If some show has a main character called Hero and over course of many seasons he is portrayed by 8 different actors, even if the character is not attached to any episode it would still show as 8 appearances which really doesn't make sense, does it?