That is what I have done and I think it is working

Correct, that's pretty much it.

With kbin you can block the instance, with Lemmy you either can a) block all their communities (subreddits) or users b) ask to get blocked by their mods or admins or c) hope your instance admin defederates them.

As someone who wants to block certain communities out of my life, like say conspiracy Q ones, I wasn‘t able to stay on Lemmy as long as we don‘t have that feature. Hope they‘ll add it eventually.

I blocked a handful of communities because I don't care to see their content, but nothing wrong with it. You do you.

On a related question How do I filter out posts that I have already read earlier on the same day. So that when I reload, I want to no see posts I already seen today.

You can also block whole instances/servers by clicking on the domain and blocking from there. It looked like a bunch of furry stuff was being posted to a specific server earlier so I block it and I haven't seen anything since

Communities or users, yes. I found the latter to be more productive when you want to rid your frontpage (is there an established term for that on lemmy just yet?) or porn, for example, since there are a few accounts (bots, most likely) cross-posting their NSFW stuff over several instances and communities. Tried blocking those individually first, but the content pops up elsewhere again.

a bit late to the party but I was is the same boat as you so here it goes:
I have not found an option to hide them without blocking but if your issue is mainly languages that you don't speak, in lemmy setting you can select to show only stuff that are in languages you select.
also you can deselect "undetermined" option for language to not get non-selected language for post that don't set their languages.

Why would you want to do that? All communities have value. It would be sad to try to block one out. We need unity, folks. Let's embrace everyone and work together to make America great again.