
Do you want me to leave the cast until you've watched the episodes to match which characters the actors/actresses played?
No. This is not necessary. They don't interfere but are no longer necessary.
See episode 1x01 again as an example - https://www.tvmaze.com/episodes/225680/scooby-doo-where-are-you-1x01-what-a-night-for-a-knight
Notice the "Additional Voices" in the Guest Cast. Those are those that weren't matched.
And notice they're a single character (or set, since it says "voices") - https://www.tvmaze.com/characters/890256/scooby-doo-where-are-you-additional-voices
John Stephenson was matched to exact character so he did not appear under "Additional Voices" under guest cast.
Now, they all appear under main cast under separate Additional Voices which is not preventing me from adding the right guest cast, but they really should all be deleted from Main Cast (all six of them). I do have all episodes from both seasons so I don't plan to use what was entered here as a reference so there really is no reason to leave them until I add all the guest cast ;) They are tied to other tv shows so deleting them from main cast won't remove any actor.