Pick your swap based on what you need most: closest taste (Gruyère/Comté) or best melt (Raclette).
Use a 1:1 ratio by weight; grate harder cheeses first so they melt smoothly.
If the substitute tastes too mild, add a small tang booster in the dish (mustard powder or a few drops of vinegar) rather than adding more cheese.
For browning, cook in a hot, dry environment (broiler or hot pan) so the top layer develops flavor like Appenzeller.
Taste near the end of cooking; Appenzeller’s punch may require slight adjustment, especially in sauces or quiches.