My game has 16 levels and 4 difficulty levels. I want a leaderboard for each combination, so 64 in total. First, I'm wondering if there is a limit to the number of leaderboards I can have. Second, Is there an API I can use to save myself all that clicking?
I've not seen a specific limit to the number of leaderboards you can have. I have tested our application with 100; and I've noticed Beat Saber has almost 300. So you should be good with 64. Albeit a pain to configure by hand..
The closest you may get is the server 2 server API. This is typically used for continued leaderboard automation. For example, deleting or creating leadboards at specific times. Or checking entries for potentially illegitimate scores.