Discourseはアラビア語のような右から左への言語のフォーラムに適していますか？

[NightMachinary]

If so, what config should I do after following Building a Discourse Community?

Update 1: I found one Persian forum using Discourse. It can’t handle English text though:

[j.jaffeux (Joffrey Jaffeux)]

There’s a site setting for this: support mixed text direction I think if enabled it’s supposed to support this.

[JimPas]

That setting is in Settings/Basic Setup/support mixed text direction. The box is unchecked by default, so you will have to check it.