Substitute for Kirsch in Leckerli (Basel Lackerli) cookies?

I would use any uncolored brandy made from distilled fruit. Himbeergeist, sliwowitz, or what you can lay your hands on.

Kirsch doesn't taste much like cherries, and I suspect that it functions more as a solvent for some of the aroma in the spices than for adding its own taste. Even though it does contribute a bit, the taste will be subtle, and other slight fruity notes from a different fruit brandy will blend with the heavy spices just as well.

In a pinch, you could use a colored brandy too, like Chantre. But it will add more of its own flavor, and while it can make a good combination, it will be further from the original than a random obstwasser.

I would avoid any liqueurs, they will add way too much foreign taste, and also won't have enough alcohol to solve the spices in the same way.

Maybe Maraschino liqueur? not the stuff that comes with clown nose cherries in it, but the real stuff. If your local liquor store sells kirsch, they might sell this. Luxardo is the brand I buy.

I haven't tried it, but I have a cherry Grand Marnier that tastes divine. Let me know how you liked it. I live in Paris. I'm not sure you can get it in the U.S., but if you can you should try it.

the closest thing to Kirsch is domestic Moonshine.