FPGA mimics hardware 1:1 without overhead, which is why it works well. This is talking about software emulation, which has to use lots of shortcuts to make it fast enough (for most machines). The N64 has a weird architecture though that makes it difficult to find shortcuts that work well.

There isn’t actually a ton of translating going on with the Switch, as it’s basically just a computer (an ARM computer, but still). The N64 had a very different architecture that doesn’t work like modern computers do. On top of that, games on it relied on low level graphics code that makes it very difficult to cheat like other emulators do.