I think Lemmy itself may be a more English-centric fediverse software, but others definitely aren’t! Misskey, for example, seems to be mostly in Japanese. There’s a long list of software using Activitypub that can be interconnected between one another at https://fedidb.org/software
Any given software will presumably bring in people who speak the language most of the documentation for it is in. There are exceptions, but I think that’s part of why so many forks exist!
Like, I’m running Calckey, a fork of Misskey which actually has some documentation in English, pretty much for that reason. I like the UI and some of the additional features, but without that fork I’d be lost as to where to even begin with setup. I still needed help, which the folks over at the Calckey support Matrix server generously provided, but I got there!
Anyway, there may well be a fork of some fediverse software made by people using the language you’re wanting to find other speakers of! I’d certainly try it!
The nice thing is, the fact that these different types of software are all federated means that we can still come find these common spaces together when we want to!
Like, I’m on my own Calckey server, and I’ve never even heard of lemmy.zip before! I’m honestly falling a bit head over heels with the degree of customization and interoperability that’s suddenly become sooo relevant!
You can do this extremely easily with a programmable keyboard. It may seem like a hefty expense, but if you use a keyboard every day there are probably many ways that a keyboard with VIA/QMK support could make a big difference to your workflow.